Difference between revisions of "PiPicoMite03"

Revision as of 16:23, 7 August 2022

Assembled board will ship as

Card Versions

There are three versions of this card
- PiPicoMite01
  - Has 16-bit port I/O expander
  - 120x70mm with (4) 6-32 mounting holes
- PiPicoMite02
  - Has 32-bit port I/O expander(s)
  - 95x95mm with (4) 6-32 mounting holes
- PiPicoMite03 (this version)
  - 99.5x69.5mm - Fits into extruded Aluminum Enclosure
  - Fully functional, reduced cost

Features

Raspberry Pi Pico
- Spare Pico pins brought to headers
  - Spare Pico pin marking on rear
VGA
- 640x480 monochrome resolution
- 320x240 colour resolution
- 1:2:1 - R:G:B - 16 colours
PS/2 Keyboard
- 5V to keyboard with voltage translator on clock/data lines
- Does not require a keyboard that runs at 3.3V
SD Card
- Full size card
- Up to 32GB
- FAT32 format
- Tested/worked
Stereo audio
- PWM with filter
- 3.5mm jack
- Cheap speakers
5V power input on USB B
- Power only (not data)
99.5mmx69.5mm outline
- Board is designed to fit into Aluminum Project Box Enclosure DIY 100*76*35mm - ebay search
- VGA, USB B (Power), 3.5mm Audio on one end
- Keyboard, SD card on the opposite end
Optional DS1307 Real time Clock (RTC) / Digital Thermometer
- On I2C1 bus (I2C2 from MMBASIC)
- 27 x 28 x 8.4mm
- DS1307 RTC
- DS18B20 Digital Thermometer

BASIC Interpreter

The PicoMiteVGA boots straight into the MMBasic prompt. At which point you can enter, edit and save the program, test BASIC commands and run the program.

MMBasic is a Microsoft BASIC compatible implementation of the BASIC language, originally written by Geoff Graham and enhanced and ported to the Pico by Peter Mather, who also designed the original PicoMite on which this design is based. It is full featured with floating point, 64-bit integers and string variables, long variable names, arrays of floats, integers or strings with multiple dimensions, extensive string handling and user defined subroutines and functions. Typically it will execute a program up to 100,000 lines per second. Embedded compiled C programs can be used for even higher performance.

Using MMBasic you can use communications protocols such as I2C or SPI to get data from a variety of sensors. You can save data to an SD card, measure voltages, detect digital inputs and drive output pins to turn on lights, relays, etc.

The emphasis with MMBasic is on ease of use and development. The development cycle is very fast with the ability to instantly switch from edit to run. Errors are listed in plain English and when an error does occur a single keystroke will invoke the built in editor with the cursor positioned on the line that caused the error.

MMBASIC Credits

Peter Mather led the project, ported the MMBasic interpreter to the Raspberry Pi Pico and wrote the hardware device drivers. Geoff Graham wrote the MMBasic interpreter and the manual. Mick Ames wrote the PIO compiler and its corresponding documentation. The VGA driver code was derived from work by Miroslav Nemecek.

Raspberry Pi Pico Pinout (Reference)

Pin Marking on Rear

Schematic

PiPicoMite03 Rev 1 Schematic

Connectors / Headers

J1 - VGA

The VGA output is 640 x 480 pixels in monochrome mode or 320 x 240 pixels in colour mode with 16 colours (1 bit for red, 2 bits for green and 1 bit for blue). The VGA output is generated using the second CPU on the RP2040 processor plus one PIO channel so it does not affect the BASIC interpreter which runs at full speed on the first CPU. A handfull of components (resistors and a couple of diodes) is all that is required to connect the VGA monitor.

From within your BASIC program you can turn pixels on/off and draw lines, boxes and circles in any colour. Text can be positioned anywhere on the screen and displayed in any colour in a variety of fonts.

The built-in editor within MMBasic works perfectly with the VGA monitor and PS2 keyboard to allow programs to be edited (with colour coded text) and saved to an SD card.

Mode 1 (640x480 monochrome) and mode 2 (320x240 16-colours).

OPTION COLOURCODE ON

J2 - USB B Power Connector

Full size USB B connector
No USB signal connections, just used for power

J3 - PS/2 Keyboard

The PS2 keyboard connects to the Raspberry Pi Pico via a level shifter and works as a normal keyboard with the function keys and arrow keys fully operational. It can be configured for the standard US layout used in the USA, Australia and New Zealand or specialised layouts used in the United Kingdom, Germany, France and Spain.

5V keyboard (VSYS)

J4 - Audio

Low Pass filter
Resistive voltage divider to get to line level
- Line Level Audio information
Two Tone Test
Play a WAV file

OPTION AUDIO GP6, GP7
PLAY WAV "file.wav"
PLAY STOP

H1 - I2C1, RTC

VBAT (N/C)
GND
VCC
I2C1_SDA (GP14)
I2C1_SCL (GP15)
DS (GP5)
SQ (M/C)

RTC / Digital Thermometer

Optional DS1307 Real Time Clocks module
- DS1307 I2C real time clock chip (RTC)
- 24C32 32K I2C EEPROM memory
- LIR2032 rechargeable Lithium battery with charging circuit
- With new battery, can power DS1307 module for 1 year
- Compact design 27 x 28 x 8.4mm
- Can install DS18B20 digital temperature sensor on module
  - Connects to GP5 pin

option system i2c2 gp14, gp15

Installs battery side up

With RTC installed
Fits within box with plenty of clearance
Can be mounted with either a 7-pin female header or RTC pins soldered directly to board

H2-H5 - Pico GVS Connectors

Spare Pico pins are brought out to GVS headers
Connectors are adjacent for GVS connections via 1x3 Dupont housings
H2/H3 adjacent to each other
- H3-1 = ADCREF
- H3-2 = GP28
- H3-3 = GP27
- H3-4 = GP26
- H3-5 = RUN
- H3-6 = GP22
H4/H5 adjacent to each other
- H4-1 = GP5
- H4-2 = GP4
- H4-3 = GP3
- H4-4 = GP2
- H4-5 = GP1
- H5-6 = GP0

SD Card

The PicoMiteVGA firmware reserves eight program storage "slots" in the Raspberry Pi Pico flash memory. Programs can be saved and retreived from these without the need for any additional storage.

For more storage SD cards can be connected with full support for these built into MMBasic including the ability to open files for reading, writing or random access and loading and saving programs. SD cards connect directly to the Raspberry Pi Pico and the firmware will work with cards up to 32GB formatted in FAT16 or FAT32. The files created can be read and written on personal computers running Windows, Linux or the Mac operating system.

OPTION SDCARD GP13, GP10, GP11, GP12

Configuration Options

> OPTION LIST
OPTION COLOURCODE ON
OPTION KEYBOARD US
OPTION SDCARD GP13, GP10, GP11, GP12
OPTION AUDIO GP6, GP7, ON PWM CHANNEL 3
OPTION SYSTEM I2C GP14, GP15

PicoMiteVGA Software

Download MMBASIC

Tested with "VGA only" versions
- Released V5.07.04
- Beta V5.07.05b2
- Copies of firmware versions - some have unstable video mode 1
TheBackshed forum - support
If the Pico does not already have MMBASIC installed
Hold button on Pico while plugging in USB Micro to PC
Drive will open
Drop VGA uf2 onto Drive
System will reboot

> print mm.ver
 5.070502

Run TeraTerm
- Connect to Serial

Configure MMBASIC

Setups
- Can copy-paste a line at a time into TeraTerm
- Some options will reboot the card

OPTION SDCARD GP13, GP10, GP11, GP12
OPTION AUDIO GP6, GP7
OPTION SYSTEM I2C2 GP14, GP15
OPTION COLOURCODE ON
OPTION KEYBOARD US

Remove USB power
Install SD card
Apply USB power

PicoMite Source code

PicoMite Source code
- Extra/replacement files for VGA

CircuitPython on PiPicoMite0x Cards

The PiPicoMite0x cards can run CircuitPython with some limitations
Card features for CircuitPython application
- SD support
- 5V input
- External I2C
CircuitPython does not have built-in support for
- VGA
- PS/2
- Audio

Factory Test Procedure

Test assembled cards using this procedure
MMBASIC is already set up on the card

Equipment

Unit Under Test (UUT)
VGA monitor
Stereo amplified speakers
PS/2 keyboard
MMBASIC SD card with contents
- Test Software repo
Raspberry Pi Pico with MMBASIC installed
PC running TeraTerm

Test SD card interface

Type

files

Returns

A:/
   <DIR>  basic
   <DIR>  bmps
   <DIR>  demos
   <DIR>  games
   <DIR>  jpegs
   <DIR>  lbcards
   <DIR>  performance
   <DIR>  wave
8 directories, 0 files

Test Sound

Loads sample4.wav file
Type

chdir "/wave"
play wav "sample4.wav"

Sound should come out of speakers
Stop with

play stop

Test Keyboard

Type on keyboard
Verify keys show up on VGA

Test VGA

Type

chdir "/demos"
load "Colours.bas"
run

Verify 16 distinct colors on VGA
Type

mode 1

Test 5V in

Connect USB B to 5V (or PC)
Remove USB Micro cable
Card should continue to run

Test I2C (Optional)

Use DS1307 RTC attached to I2C J1

option system i2c gp14, gp15
rtc gettime
print time$

Combined Copy/Paste

Above tests can be copy/pasted

files

chdir "/wave"
play wav "sample4.wav"

play stop

chdir "/demos"
load "Colours.bas"
run

mode 1

option system i2c gp14, gp15
rtc gettime
print time$

Enclosure

Panel cutouts
- PiPicoMite03 Panel Cutouts pdf file
- Print and use to cut the panel holes

99.5mmx69.5mm outline
- Board is designed to fit into Aluminum Project Box Enclosure DIY 100*76*35mm - ebay search
- VGA, USB B (Power), 3.5mm Audio on one end
- Keyboard, SD card on the opposite end

Enclosure cross-section

Mechanicals

Dimensions to approx. connector centers (and SD adapter slot)
Enclosure fits 70mmx100mm card
- The PiPicoMite03 card is slightly undersized (0.5mm)
- Still fit in slots but allows for some enclosure mechanical variances

Issues

Rev 1

Tested, working, no issues

Assembly Sheet

Make sure you build with the current revision assembly sheet
- Revision is marked on the rear of the card
PiPicoMite03 Rev1 Assembly Sheet