Fullscreen HTML5Med Res (??MB)HTML4

PICO/2/COMPUTER > Design and firmware by Peter Mather > Words and MMBasic by Geoff Graham This computer uses the latest and greatest Raspberry Pi Pico 2. Like the PicoMite, it can be programmed in MMBasic, but it has a lot of extra features like a HDMI video connector, multiple USB sockets for devices like keyboards, mice and game controllers, and an audio output. I n our February issue this year, we introduced the latest version of the PicoMite firmware for the Raspberry Pi Pico 2. It includes advanced features such as support for HDMI video and USB keyboards. In this design, we bring these elements together to provide a high performance ‘boot to BASIC’ computer that is fast and very capable. This type of computer was popular in the 1970s and 1980s (and still is today!), including examples such as the Apple ][, Commodore 64, Tandy TRS-80 and many others. These computers all included a BASIC interpreter and, when the computer was powered up, booted straight to the BASIC command prompt. There, 24 Silicon Chip you could enter programs, test commands and immediately be productive. The Pico 2 Computer is just as easy and fun to use but much, much more powerful! It includes everything that you need to get started. That makes it ideal for learning to program, entertaining/teaching children about computers and just having fun exploring its capabilities. This Computer can also be used for more than just running calculations. You can use it to interact with the physical world, including measuring voltages, detecting switch closures and driving outputs to light LEDs, play music, generate sound effects and more. Australia's electronics magazine This is a ‘reference design’. By this, we mean that it can be used as a template for a computer of your own design with the best of its features. If you want to ‘roll your own’, you are welcome to take elements of this design, modify them as needed and incorporate them in your own creation. You can also simply build this computer as-is, and you will have a capable and high-performance boot-to-­BASIC computer. Features The video output is HDMI-compatible in one of three resolutions: 640 × 480, 1280 × 720 (wide-screen) or 1024 × 768 pixels. At these resolutions, the siliconchip.com.au output is monochrome. However, by using the MODE command, you can select more colours at lower resolutions. The built-in BASIC program editor uses the full resolution yet, by using the TILE command, it will colour the characters for you. For example, it uses cyan for keywords, green for comments etc. This makes for a colourful and intuitive editing experience at the full screen resolution. The USB keyboard input has full support for the function keys, arrow keys etc. Our previous computers used PS/2 keyboards, but they are becoming difficult to find these days, so support for a USB keyboard is a welcome addition. This facility extends to wireless keyboards with a USB dongle, so you do not need to be tethered by a cable. This design includes a four-port USB hub with four USB Type-A sockets so that you can add additional devices – primarily a USB mouse and USB game controllers. The mouse is most useful when using the built in MMBasic program editor, where it gives you an almost GUI-like experience, with the ability to position the insert point and copy and paste – all using the mouse. As with the keyboard, you can also use a wireless mouse. One or more USB game controllers can also be plugged in. Within a BASIC program, you can query the position of the joystick, the state of the buttons etc. So, if you are into writing games, you can create the full arcade (or home games console) experience. More features A highly accurate battery-backed real-time clock is included in the design. This means that the Pico 2 Computer will always know the correct time. You might use this within a program, but it is also useful in that all files created by MMBasic will be stamped with correct creation times. Speaking of files, the Pico 2 Computer includes a microSD card socket with support for cards formatted in FAT16 or FAT32, and capacities of up to 32GB. Files written on these can be read/written by Windows, Apple and Linux computers, so this is an easy way of transferring files to and from larger desktop or portable computers. siliconchip.com.au The Pico 2 Computer is built on a 90 × 100mm PCB. It uses surface-mounting components and can be hand-built or machine-assembled. The only component that must be soldered by hand is the Raspberry Pi Pico 2 module. Built into the PicoMite firmware is an internal drive (called drive A:) that uses the flash memory in the Raspberry Pi Pico 2. This is about 2MiB (ample for normal use), so this is another place to save program and data files, particularly during program development. On the back panel is a stereo audio output connector. This provides a high-quality audio output of about 3V peak-to-peak, suitable for feeding a HiFi system or amplified speakers. Within BASIC programs, you can create various tones and sound effects as well as stream music files in WAV, FLAC, MP3 or MOD formats located on the internal filesystem or SD card. To connect to the outside world, the Pico 2 Computer has 14 input/output (I/O) pins that can be used as digital inputs or outputs. As inputs, they can monitor switches and sensors (humidity, temperature, location and more). As digital outputs, these I/O pins can drive LEDs and powered relays to switch heavy loads. Three of these pins can also measure voltages, so you can monitor signals Australia's electronics magazine from the analog world, such as battery charge levels. The PicoMite firmware We described the new PicoMite firmware for the Raspberry Pi Pico 2 in detail in the February 2025 issue (siliconchip.au/Article/17729). At its core is the MMBasic interpreter, which makes it easy to write programs in the BASIC language. BASIC is an easy-to-learn language so it, and the Pico 2 Computer, are ideal for someone who wants to get into programming and learn the basics. At the same time, it is quite powerful, so you can develop large and complex programs ranging from controlling physical processes to calculating the positions of the planets. It is also an ideal platform for creating graphical computer games, ranging from classics such as Tetris and Chess through to more advanced 3D simulations. The PicoMite firmware includes support for multiple video layers and graphical objects such as sprites. For anyone familiar with the home April 2025  25 computers of the 1970s and 1980s, this will all be recognisable. The difference is that the Pico 2 Computer is much faster and has many more resources that these early computers. At roughly 100 times faster and with 10 times the memory, this computer is something that the programmers of the 1970s and 1980s could only dream about! The PicoMite firmware is fully self-contained. You do not need an operating system or other external programs. It includes its own feature-rich 26 Silicon Chip program editor and drivers for all the I/O devices (SD cards, clock, audio, USB devices, video display etc). Circuit details As shown in Fig.1, at the heart of the Pico 2 Computer is the Raspberry Pi Pico 2 module. It is amazing value; for a little over $8, you get a dual-core 32-bit CPU capable of running at up to 400MHz, including 520KiB of built in RAM. A separate chip on the module provides 4MiB of flash memory for programs and general storage. Australia's electronics magazine This module runs the PicoMite firmware, including the BASIC interpreter, with the rest of the circuit being primarily used to interface it to the video, keyboard and some specialised components. A supervisor device (MAX809R) monitors the 3.3V power rail (VDD) and provides a reset signal to the RP2350A microcontroller to ensure that it is cleanly shut down when the power is removed. It will drive the reset pin of the Pico 2 low within 65µs of the 3.3V power rail falling below siliconchip.com.au circuits and an ingenious scheme for driving the five status LEDs using just three outputs. The circuit includes a 12MHz crystal oscillator that is used by the CH334F to create the accurate timing required by the USB standard. To load MMBasic on the Pico 2, you need to disconnect the hub and directly access the USB interface on the Pico 2. Of course, you can do this before mounting the Pico 2 module but it may become necessary to do this again later (eg, to update the firmware). So jumpers JP1 & JP2 allow you to isolate the hub, and you can use the extra micro-USB connector on the PCB’s edge (CON5). Serial console Fig.1: the Raspberry Pi Pico 2 module is at the core of this design, with the rest of the circuit providing the video, keyboard, microSD and external I/O interfaces. Other features include a real-time clock, an integrated USB four-port hub and a dedicated serial-to-USB bridge for the serial console. 2.63V, and will maintain it low until it is above that threshold for at least 140ms. USB interface The PicoMite firmware uses the USB interface integrated in the RP2350A processor on the Pico 2 to provide support for a USB keyboard. However, in this design, we also wanted to provide for a USB mouse and gamepads in addition to the keyboard. To do this, the Pico 2 Computer includes a CH334F integrated USB 2.0 four-port hub. siliconchip.com.au The connection between the CH334F and the USB interface on the Raspberry Pi Pico 2 is made by soldering through three holes on the PCB to connect to test pads on the underside of the Pico 2 module. These pads provide the USB interface, meaning we do not need to plug anything into the module’s USB connector. The CH334F includes the USB 2.0 driver circuits (called USB PHYs) that connect to the four USB Type-A sockets on the front panel. The CH334F also includes the required protection Australia's electronics magazine Because the USB interface on the Raspberry Pi Pico 2 is used for communicating with various USB devices such as the keyboard, it cannot be used for the serial-over-USB console used by the BASIC interpreter to communicate with a desktop or laptop computer. In a self-contained computer like this one, the serial console is not critically important, as the MMBasic console output will display on your HDMI monitor anyway. However, having the serial console is handy for connecting to a desktop or laptop computer, so the Pico 2 Computer uses a CH340C serial to USB bridge to provide the serial-over-USB console interface. The CH340C converts the TTL asynchronous serial signal from the Pico 2 (on pins GP8 and GP9) to a USB 2.0 signal using the CDC (Communication Device Class) protocol. The CH340 is in an SMD SOP-16 package that includes the crystal and oscillator required for USB timing. This chip (and the CH341, which is similar) is used in many Arduino Nano clones, and the driver for it is included by default in Windows 10/11 and Linux. Also, many macOS builds include the driver. Video and audio The HDMI connector is driven by output pins on the Raspberry Pi Pico 2 via 220W resistors. The Pico 2 and the HDMI connector are positioned close to each other to reduce the track lengths and the chances of crosstalk and interference. The stereo audio output is generated April 2025  27 Power switch 14 GPIO (General Purpose I/O) + 3.3V & 5V pins Reset switch Stereo Audio 1V RMS HDMI Video (up to 1280 × 720) USB-C power input and serial console Raspberry Pi Pico 2 with BASIC interpreter Built-in editor Real-time clock using a CR2032 cell 180KiB of program space 228KiB of RAM Four-port USB hub IC MicroSD card up to 32GB Micro USB for firmware loading 4 × USB ports The Pico 2 Computer is a fully featured reference design with HDMI video, four USB ports for keyboards, mice and game controllers, a battery-backed real-time clock, microSD card socket and 14 externally available I/O pins. by the PicoMite firmware using pins GP10 and GP11. It is a PWM (pulsewidth modulated) signal that passes through a multi-pole low-pass filter to remove the carrier frequency. This filter, along with the low-noise regulator used to generate the 3.3V rails, results in a low noise audio signal capable of reproducing tones, sound effects and music with good fidelity from 10Hz to 15kHz. The maximum audio output level is 3V peak-to-peak (approximately 1V RMS) and is intended to be fed to amplified speakers. The amplifier used must have a capacitor-coupled input (most do), as the output signal has a DC offset. Timekeeping is provided by a DS3231 real-time clock (RTC), which is an extremely accurate timekeeper with an integrated temperature-­ compensated crystal oscillator (TCXO). It will typically keep the time accurate within a few seconds per month. It also includes a comparator circuit that monitors the status of the power supply and will automatically 28 Silicon Chip switch to the backup battery to keep the clock running when power is removed. The battery used for this is a non-­rechargeable 210mAh 3V lithium coin cell (CR2032), which should be good for many years of use. External I/O There are 14 input/output pins on the rear panel of the Computer that connect to pins on the Pico 2, which can be used as digital inputs or digital outputs. Some of these can also be used as PWM outputs as well as I2C, SPI and asynchronous serial communications channels. Three of these pins can be used as analog inputs, with the ability to measure voltage in the range of 0-3.3V. All these features are configured by the BASIC program running on the computer. The last component of note is the microSD card socket, which connects to another set of I/O pins on the Pico 2. The PicoMite firmware uses the SPI protocol to talk to the card and this is not influenced by the card type, so all Australia's electronics magazine types (Class 4, 10, UHS-1 etc) with a capacity of up to 32GB are supported. Power supply The power requirement for the Pico 2 Computer is 5V (typically drawing 170mA), which can be supplied via a normal USB charger with a USB Type-C plug. This 5V supply is used by the physical USB ports, but the rest of the computer runs from 3.3V, and this is provided by an AMS1117 low-dropout three-terminal linear regulator. There are many other compatible regulators, such as the LD1117, NCP1117, STC1117 etc. They may have varying specifications like the maximum input voltage, but as the input supply is 5V in this circuit, any of those types would be suitable. The Pico 2 also has an onboard regulator capable of supplying the required 3.3V, but this is a switching regulator and the electrical noise generated by its operation causes noise on the audio output. It also degrades the ability of the ADC inputs to measure voltages accurately. That is why this design siliconchip.com.au You can also find the most up-to-date information on the Pico 2 Computer (including design files and firmware) at https:// geoffg.net/ picomitevga. html uses the dedicated linear regulator and the onboard switching regulator is disabled. Purchasing an assembled board While the Pico 2 Computer can be built by hand, it takes some dexterity. There are many small surface-­ mounting components, including the USB hub, which comes in a quad flat no-lead (QFN) package. There are also some passives as small as 1.2 × 0.6mm. If you have the skill, it is feasible to hand-solder these components. However, this project is primarily designed for automated assembly. We therefore won’t give any detailed assembly instructions. If you have the required skills, you should be able to use the overlay diagram (Fig.2) to build your board. JLCPCB is a major PCB fabricator based in China. Through their LCSC supply arm, they can even supply the components and solder them to the PCB they make using solder paste applicators, pick-and-place machines Fig.2: here is the and reflow ovens. PCB overlay in At the time of writing, JLCPCB will case you want make the PCB, supply, mount and to assemble the solder all the components except the board yourself. Pico 2 for about $150 for two boards This also shows (plus three spare PCBs). Over time, how to orientate this price may vary with exchange the Pico 2 even if you’re using rates and other factors, but it is still a a pre-built good price for an almost fully assemboard. If you’re bled computer. adding the parts This assembly even includes large manually, take components, such as the conneccare with the tors and switches that must be hand-­ orientations of soldered. The only assembly required the diodes, LEDs, by you is to solder the Raspberry Pi ICs and crystal. Pico 2 and load the firmware. Then There are three you are ready to go. You could remove different sizes of resistors some of the larger components from and four of the BOM (Bill of Materials) given to capacitors; the JLCPCB and save some money by solsmallest in both dering them yourself. cases (1.2 × The process of ordering the assem0.6mm) can be bled boards is simple. First, download hand-soldered, three files from the Silicon Chip webbut not easily. site. These are “Pico 2 Computer Gerbers.zip”, which contains the design files for the PCB, “Pico 2 Computer BOM.xlsx”, which is the Bill of Materials, and “Pico 2 Computer CPL.xlsx”, which has the types and positions of the components on the PCB. On the JLCPCB website (https:// jlcpcb.com), click on the Instant Quote button and drag the “Pico 2 Computer The front of the Pico 2 Computer mounted in its small matching instrument Gerbers.zip” file onto the blue button case. siliconchip.com.au Australia's electronics magazine April 2025  29 labelled “Add Gerber File”. JLCPCB will then read the files and display an image of the front and back of the PCB. The website will also fill in the defaults for the PCB, such as thickness, colour etc. You can leave these as suggested. Scroll to the bottom of the page and select “PCB Assembly”. This will display more options, which you can leave at their default, other than selecting how many boards that you want them to fully assemble (I recommend two). Then click on the “Next” button on the right and the website will display a new page showing a large image of the board. Then click on the “Next” button again. On the next page, drag and drop the “Pico 2 Computer BOM.xlsx” file onto the button labelled “Add BOM File”, and drag and drop the “Pico 2 Computer CPL.xlsx” onto the “Add CPL File” button. Then click on the “Process BOM and CPL” button. The website will then show a list of all the parts required, the quantity that JLCPCB has in stock and their associated prices. All the components on the Bill of Materials are JLCPCB catalog items, and they should all be in stock. If, for some reason, a component is not available, you have the choice of leaving it out and sourcing it yourself. Alternatively, you could search JLCPCB for a substitute, perhaps one with a slightly different specification. At this stage, you can also choose to omit components that you wish to hand-solder to save cost. At the bottom of the page, click “NEXT” and you will be taken to a page that shows an image of the completed board. Clicking “NEXT” again will take you to the final quote detailing the total price. If you are happy, click “SAVE TO CART” and then proceed to give them your address and pay. Mounting the Pico 2 The one component that JLCPCB does not include in the assembly is the Raspberry Pi Pico 2 module. This is surface-mounted flat on the PCB. A special characteristic involved in this design is that you need to solder through three holes in the PCB to connect the USB pads on the underside of the Raspberry Pi Pico 2 module to the PCB. For that to work, you need to closely follow the instructions below. First, accurately position the Pico 2 module on its pads and, while holding it very flat on the PCB, tack-solder one corner pad. Check the alignment and, if it is still correct and the module is still flat on the PCB, tack-solder the opposite pin. With the Pico 2 module securely fastened, turn over the PCB and locate the three solder pads with plated through-holes identified as A, B and C in Photo 1. Apply plenty of liquid or paste flux in these holes and melt fine-gauge solder wire into them. The solder should flow through the holes and adhere to the three gold-plated pads on the underside of the Raspberry Pi Pico 2 module. While you are doing this, identify a similar plated through-hole designated D in Photo 1 and similarly apply flux and run solder into this hole. This connects to a heatsink pad on the underside of the CH334F USB 2.0 four-port hub. Soldering to this pad will assist in keeping that chip cool. Then work down the Raspberry Pi Pico 2 and solder the remaining solder pads. Finally, return to the first two pads that were tack-soldered and re-solder them securely. Figs.3 & 4: these are the panel cutouts required for the end panels of the instrument case. Pre-made panels are available that already have these holes neatly made and labels printed on them. All dimensions are in millimetres. Figs.5 & 6: the artwork for the end panels of the instrument case at actual size. You can also download these as a PDF from the Silicon Chip website (siliconchip.com.au/ Shop/11/1834). See siliconchip.au/ Help/FrontPanels for details on producing and attaching labels. 30 Silicon Chip Australia's electronics magazine siliconchip.com.au Finishing assembly To finish the assembly, you need to place jumpers between pins 1 & 2 and pins 3 & 4 on the four jumper pins near the CH334F four-port hub chip (IC20). These connect the hub chip to the USB RP2530A processor and only need to be removed when you are loading or upgrading the PicoMite firmware. Jumpers also need to be placed on the group marked SELECT SD PINS. For normal operation, place jumpers to connect GP26, GP27 and GP28 to their respective centre pins. These can be changed to GP2, GP3 and GP4 if you want to have the analog input pins usable on the external I/O port. The completed PCB can be used without an enclosure. In that case, you can attach plastic tapped spacers or standoffs to the four mounting holes to stop it from scratching your desk. However, the PCB is designed to fit in a Multicomp MCRM2015S enclosure available from element14/Farnell. The compatible Hammond RM2015S is available from DigiKey, Mouser etc. If you’re putting the board in one of these cases, you will need to make the cutouts in the front and rear panels as detailed in Figs.3 & 4, then print and apply the artwork depicted in Figs.5 & 6. Alternatively, you could purchase PCB-based front and rear panels from the Silicon Chip Online Shop and save yourself the effort of making all those holes (this also guarantees neatness). The labels will be printed on those panels, although they will only be labelled in white. These panels will also be included our kits (along with the pre-assembled PCB). Photo 1: the A, B & C solder pads connect to associated gold-plated pads on the underside of the Pico 2. Hole D connects to a heatsink pad on the underside of the CH334F USB 2.0 four-port hub. All four should be fluxed and solder run into the hole to make the connections. Loading the firmware With the hardware assembled, you can load the PicoMite firmware. For this, you need the firmware file “PicoMiteHDMIUSBV6.00.01.uf2”, which is included in the PicoMite firmware zip file downloadable from the Silicon Chip website (siliconchip. au/Shop/6/833) or the author’s website at http://geoffg.net/picomite.html (scroll to the bottom of the page). To load the firmware, you need to remove the two jumpers previously placed on the header near the CH334F four port hub chip. Then, while holding down the white button marked BOOTSEL on top of the Raspberry Pi Pico 2 module, plug your desktop or laptop computer into the connector siliconchip.com.au The Pico 2 Computer can be used without a case. With feet in the corners, it is at home driving a HDMI monitor with a USB keyboard, mouse & game controllers. The rear of the Pico 2 Computer mounted in its small matching instrument case. Australia's electronics magazine April 2025  31 For x = 0 To 16 For y = 0 To 16 For i = 0 To 16 Read d(x, y, i) ‘ load the shortest path database Next i Next y Next x StartGame: If TestMode <> 1 Then StartScreen Score = 0 NbrMen = 3 NextOrange = OrangeLevel OrangeX = 0 : OrangeY = 0 BonusPacMan = BonusLevel Level = 0 NewLevel: LoadData LostALife: ‘ scramble the ghost colours For i = 1 To 10 j = Int(Rnd * 4) : k = Int(Rnd * 4) l = GhostColour(j) : GhostColour(j) = GhostColour(k) Next i ‘ draw the ghosts on the screen and save them as a BLIT object F1: Save F2:Run F3:Find F4:Mark F5:Paste Ln: 27 Col: 55 INS Screen 1: the built-in editor is colour coded with cyan for keywords, green for comments etc. It includes a search facility, a clipboard for copy and paste, automatic indenting and more. If an error occurs, the editor will start with the cursor placed on the program line that caused the error. Screen 2: the Mandelbrot set (a fractal) was a favourite test for the home computer of the 1970s through to the 1990s. In the early days, it took some 24 hours to calculate it! The Pico 2 Computer drew this comparatively highresolution version in a little over four minutes. Coin Cell Precautions marked PROG on the front of the Pico 2 Computer’s PCB. When you do this, the Raspberry Pi Pico 2 should connect to your computer and create a virtual drive, as if you had plugged in a USB memory stick (you can ignore any files on this ‘drive’). Then copy the firmware file (with the extension .uf2) to this virtual drive. Once completed, the Pico 2 will restart and the LED on it will blink slowly, indicating that the PicoMite firmware is running. While the virtual drive created by the Raspberry Pi Pico looks like a USB memory stick, it is not; the firmware file will vanish once copied, and if you try copying any other type of file to it, that file will be ignored. If you later upgrade the firmware, you should be aware that this operation may erase all the flash memory, including the current program and any files in drive A:. So ensure that you back up all of your data before upgrading. Final setup Replace the pins on the jumper group near the CH334F chip and plug in a USB keyboard and HDMI monitor. Apply power to the USB Type-C connector on the rear edge of the PCB and depress the ON/OFF switch beside it to switch on the computer. You should then be greeted with the firmware’s copyright notice on the HDMI monitor. With the firmware loaded and the monitor and keyboard connected, you should see the command prompt (a greater than symbol, ‘>’) on the monitor. At this point, you can enter commands, run programs etc. However, before you jump in, two additional steps should be completed. The first is to enter the command OPTION RESET HDMIUSB. This will set the firmware options to suit this design and will save you a lot of time from having to enter each option individually. Following this, if you want to use the alternative SD card connection pins, enter the following commands at the command prompt: OPTION SDCARD DISABLE OPTION SDCARD GP22, GP2, GP3, GP4 If not mounting the Pico 2 Computer in a case, care should be taken so that the device is not left anywhere that children could get hold of it. Coin cells are very dangerous to children if they swallow them, and some will do so given the opportunity. Make sure that can't happen! The final action is to set the date and time in the real-time clock. The command to do this is entered at the command prompt and is: Australia's electronics magazine siliconchip.com.au 32 Silicon Chip RTC SETTIME year, month, day, hour, minute, second Parts List – Pico 2 Computer While most computers will already have drivers for the chip used for the console, if you find you do need a driver, help is available at https:// sparks.gogo.co.nz/ch340.html Note that the PicoMite firmware sets the console to 115,200 baud, so the terminal emulator running on your desktop computer will need to be set to this speed. In the meantime, have fun with your new computer! SC 1 double-sided PCB coded 07104251, 90 × 100mm 1 pair of front & rear panels made from FR4 PCB material with a black solder mask and white silkscreen printing (optional) [Silicon Chip SC7453] 1 Raspberry Pi Pico 2 (RP2350A) without header pins (MOD1) 1 Multicomp MCRM2015S or Hammond RM2015S instrument case (optional) OR 4 M3-tapped Nylon spacers and M3 × 6mm panhead machine screws (for feet) 1 CR2032 3V lithium coin cell (BAT1) 1 30V 750mA resettable polyfuse M3216 (PTC1) [BHFuse BSMD1206-075-30V] 1 latching right-angle PCB-mount pushbutton (S13) [XKB Connectivity XKB5858-Z-E] 1 right-angle tactile pushbutton switch with 6mm actuator (S15) [HCTL TC-6615-7.5-260G] 1 12MHz 20pF 10ppm 4-pin SMD crystal, 3.2 × 2.5mm (X1) [YXC X322512MSB4SI] Connectors 1 CR2032 cell holder (BAT1) [Myoung BS-04-A1BJ005] 1 HDMI socket (CON1) [HCTL HDMI-01] 1 USB-C socket (CON2) [Kinghelm KH-TYPE-C-16P] 2 right-angle horizontal stacked USB Type-A sockets (CON3, CON4) [Shou Han AF SS-JB17.6] 1 USB micro-B socket (CON5) [Shou Han MicroXNJ] 1 microSD card socket (CON6) [Shou Han TF PUSH] 1 SMD stereo audio jack socket (CON7) [Shou Han PJ-313 5JCJ] 1 2×12-pin right-angle 2.54mm-pitch header (CON23) [HanElectricity 2541WR-2x12P] 1 2×2-pin 2.54mm-pitch header (JP1, JP2) [JST RF-H042TD-1190(LF)(SN)] 1 3×3-pin 2.54mm-pitch header (LK1-LK3) [HCTL PZ254-3-03-Z-2.5-G0] 5 jumper shunts (JP1-JP2, LK1-LK3) Semiconductors 1 CH340C serial/USB bridge, SOIC-16 (IC7) 1 DS3231MZ real-time clock & calendar, SOIC-8 (IC19) 1 CH334F quad USB hub, QFN-24 (IC20) 1 MAX809R reset supervisor IC, SOT-23-3 (IC24) 1 AMS1117-3.3 or equivalent 3.3V low-dropout linear regulator, SOT-223-3 (REG1) 1 MDD2301 P-channel Mosfet, SOT-23-3 (Q1) 1 red SMD LED, M1608/0603 size (LED2) [KT-0603R] 5 green SMD LEDs, M2012/0805 size (LED3-LED7) [KT-0805G] 2 SS14 40V 1A schottky diodes, SMA package (D1, D2) Inductors & ferrite beads 1 M2012/0805 multi-layer ferrite bead (FB12) [Murata BLM21PG221SN1D] 2 10μH 15mA 1.15W M1608/0805 SMD inductors (L22, L23) [Sunlord SDFL2012S100KTF] 2 4.7mH 110mA 32.5W 5×5mm SMD inductors (L26, L27) [YJYCoin YNR5040-472M] Capacitors 2 220μF 10V D-case solid tantalum electrolytic [Kyocera AVX TAJD227K010RNJ] 3 10μF 50V X5R M3216/1206 ceramic [Samsung CL31A106KBHNNNE] 7 100nF 16V M1206/0402 X7R ceramic [Samsung CL05B104KO5NNNC] 6 33nF 50V M2012/0805 X7R ceramic [FH 0805B333K500NT] 2 2.2nF 50V M2012/0805 NP0/C0G ceramic [Samsung CL21C222JBFNNNE] 2 470pF 50V M1608/0603 X7R ceramic [FH 0603B471K500NT] Resistors (all SMD 1%) 1 1MW (M1206/0402 size) Pico/2/Computer Pre-Made 1 15kW (M1608/0603 size) Board (SC7468; $120 + post): 1 12kW (M1608/0603 size) 2 10kW (M2012/0805 size) Includes an assembled PCB, 2 5.1kW (M1206/0402 size) Raspberry Pi Pico 2 (which 1 4.7kW (M2012/0805 size) you need to attach to the PCB 1 470W (M1608/0603 size) yourself) and front & rear panels. 2 220W (M2012/0805 size) We currently plan to only supply 11 220W (M1608/0603 size) a limited amount of these kits. 1 2.2W (M2012/0805 size) siliconchip.com.au Australia's electronics magazine Here, ‘year’ is two or four digits and ‘hour’ is in 24 hour notation. Don’t forget to insert a CR2032 cell in the holder so it will keep time when the power is switched off. Using MMBasic On startup, MMBasic will issue the command prompt and wait for you to enter something. It will also return to the command prompt if your program ends or encounters an error. When the command prompt is shown, you have a wide range of commands that you can enter and execute. For example, you can list the program held in memory (LIST) or edit it (EDIT), or perhaps check the memory usage (MEMORY). The command RUN instructs MMBasic to run the program currently held in program memory. All of these and more are described in detail in the PicoMite User Manual, which is included in the firmware download package. Almost any command can be entered at the command prompt, and this is a good way to test a command to see how it works. A simple example is the PRINT command, which will simply print the result of a calculation. You can try this by entering the following at the command prompt: PRINT 1/7 MMBasic will print out the result of dividing 1 by 7 (ie, the number 0.1428571429) before returning to the command prompt. If you are new to the BASIC programming language, refer to Appendix I at the back of the PicoMite User Manual. This is a comprehensive tutorial on the language, which will take you through the fundamentals in an easyto-read format with lots of examples. Using the serial console April 2025  33