PiPicoMite02

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 (this version)
    • Has 32-bit port I/O expander(s)
    • 95x95mm with (4) 6-32 mounting holes
  • PiPicoMite03
    • 99.5x69.5mm - Fits into extruded Aluminum Enclosure
    • Fully functional, reduced cost

Features

• Raspberry Pi Pico
  • All Pico pins brought to headers
  • 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
  • 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
• 32-bit GPIO
  • (2) MCP23017 Datasheet - Rev D
  • MCP23017... LOST TWO INPUTS
    • MCP23017 now a 14/16-bit expander, with two of the pins (GPA7 and GPB7) losing their input capabilities
    • The chips look the same, are called the same, and act mostly the same — if you don’t download the latest version of the datasheet (Revision D), you’d never know that there’s been a change* 16-bit General Purpose I/O (GPIO)
  • I2C1 (I2C2 from MMBASIC)
  • DB-37 Female connector
  • Jumper selectable terminators
• I2C0 connector
  • With Interrupt line
• Power options
  • 5V power input
    • USB Micro on Pico card
    • USB B
    • 0.1" pitch header
  • 3.3V output header
• 95mmx95mm outline ODAS standard
• (4) 6-32 Mounting holes

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

• PiPicoMite02 Rev 1 Schematic

Connectors

J1 - I2C (RTC, etc.)

1. INT (GP3)
2. SCL (GP1)
3. SDA (GP0)
4. VCC
5. GND

Can use Real Time Clocks using the PCF8563, DS1307, DS3231 or DS3232 chips means that the time is always accurately known.

J2, J3 Pico Connectors

Pico Function Mapping

GP	FUNCTION	PICO PIN		GP	FUNCTION	PICO PIN
GP0	I2C0_SDA (J1-I2C)	1		GP16	VGA_HSYNC	21
GP1	I2C0_SCL (J1-I2C)	2		GP17	VGA_VSYNC	22
GP2	I2C1_INT (MCP23017 if J4 in)	4		GP18	VGA_BLU	24
GP3	I2C0_INT (J1-I2C)	5		GP19	VGA_GRN_LO	25
GP4	SPARE	6		GP20	VGA_GRN_HI	26
GP5	SPARE	7		GP21	VGA_RED	27
GP6	AUDIO-L	9		GP22	SPARE	29
GP7	AUDIO-R	10		RUN	RUN/RESET*	30
GP8	PS2_CLK	11		GP26	SPARE	31
GP9	PS2_DATA	12		GP27	SPARE	32
GP10	SD_SCK	14		GP28	SPARE	34
GP11	SD_MOSI	15		ADC	ADCREF	35
GP12	SD_MISO	16		VEN3	3.3V ENABLE	37
GP13	SD_SLVSEL	17		3.3V	POWER_3.3V	36
GP14	I2C1_SDA (2xMCP23017)	19		VSYS	PS2_5V	39
GP15	I2C1_SCL (2xMCP23017)	20

J4- MCP23017s - I2C Interrupt 2

• Install jumper to connect INTA interrupts from MCP23017s to GP2 on Pico
• No Pull-up

J5 - I2C2 Terminators

• Install shunts to terminate SDA, SCL signals
• Commands

SETPIN GP14, GP15, I2C2
I2C2 OPEN 400, 100
I2C2 WRITE &H20, OC, LEN, B0[, B1...]
I2C2 READ &H20, OX, LEN, BUFF()

• &H20 - I2C Address 0x20
• OC: 0=terminate after, 1=chain next
• len - Length of buffer (normally 1 for receive)
• B0,B1... Bytes to send
• BUFF() - receive buffer

J6 - 3.3V Power Out

J7 - 5V Input

• Useful for external 5V

J8 - Audio

• Two Tone Test
• Play a WAV file

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

J9 - 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.

J10 - USB B Power Connectors

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

J11 - 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.

P1 - 32-bit GPIO

• Card has connector (DB-37 female)
  • DC-37 Male Solder cup potential mating connector
• MCP23017... LOST TWO INPUTS
  • MCP23017 now a 14/16-bit expander, with two of the pins (GPA7 and GPB7) losing their input capabilities
  • The chips look the same, are called the same, and act mostly the same — if you don’t download the latest version of the datasheet (Revision D), you’d never know that there’s been a change
  • MCP23017 Datasheet - Rev D

SetPin GP14, GP15, I2C2
I2C2 OPEN 400, 100
I2C2 WRITE &H20, 0, 2, &H00, &H00
I2C2 WRITE &H20, 0, 2, &H01, &H00
I2C2 WRITE &H21, 0, 2, &H00, &H00
I2C2 WRITE &H21, 0, 2, &H01, &H00

PiPicoMite02 DB37 to DB37RIBBON Pins

• DB37RIBBON

P1	Chip	Port	Bit	DB37RIBBON		P1	Chip	Port	Bit	DB37RIBBON
1			GND	37		20			GND	36
2	0	B	7	35		21	0	A	0	34
3	0	B	6	33		22	0	A	1	32
4	0	B	5	31		23	0	A	2	30
5	0	B	4	29		24	0	A	3	28
6	0	B	3	27		25	0	A	4	26
7	0	B	2	25		26	0	A	5	24
8	0	B	1	23		27	0	A	6	22
9	0	B	0	21		28	0	A	7	20
10			N/C	19		29	1	B	7	18
11	1	A	0	17		30	1	B	6	16
12	1	A	1	15		31	1	B	5	14
13	1	A	2	13		32	1	B	4	12
14	1	A	3	11		33	1	B	3	10
15	1	A	4	9		34	1	B	2	8
16	1	A	5	7		35	1	B	1	6
17	1	A	6	5		36	1	B	0	4
18	1	A	7	3		37			+3.3V	2
19			+3.3V	1

SD1 - 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 gp0, gp1

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
  • First two will reboot card

OPTION SDCARD GP13, GP10, GP11, GP12
OPTION AUDIO GP6, GP7
OPTION COLOURCODE ON
OPTION POWER PWM

• Remove USB power
• Install SD card
• Apply USB power

PicoMite Source code

• It's not necessary to build the source code since there are .uf2 files
• PicoMite Source code
  • Extra/replacement files for VGA

On-Board 32-bit Port Expanders Example Code

Example code that uses the (2) MCP23017 Port Expanders on the card

• MCP23017 Datasheet

GPIO32-01.bas

• GPIO32-01.bas
  • Test the (2) MCP23017 parts on the PiPicoMite02 card
  • Light all of the output pins one at a time
  • Alternate patterns then bounce a LED

GPIO32_Bits.bas

• GPIO32_Bits.bas
  • Provides Arduino style DigitalRead, DigitalWrite, PinMode functions

Land Boards Card Test Code

External MCP23017 I2C Demo Code

• Test external I2C I/O connector
• External PROTO16-I2C card
• External PIO16-01.BAS - GitHub repo
• Set all 16 GPIO pins as outputs
• Write alternate patterns, bounce a 1 across the outputs

SetPin GP14, GP15, I2C2
I2C2 OPEN 400, 100
I2C2 WRITE &H20, 0, 2, &H00, &H00
I2C2 WRITE &H20, 0, 2, &H01, &H00
I2C2 WRITE &H20, 0, 2, &H14, &H55
I2C2 WRITE &H20, 0, 2, &H15, &HAA
Pause 1000
I2C2 WRITE &H20, 0, 2, &H14, &HAA
I2C2 WRITE &H20, 0, 2, &H15, &H55
I2C2 CLOSE

MCP23008 Demo Code

• I2CIO-8 card
• MCP23008 Datasheet
• I2CIO8-Bounce.bas - GitHub repo
  • Bounce a bit across the 4 LEDs
• I2CIO8-ReadWrite.bas - GitHub repo
• Read 4 jumpers and write out LEDs

CircuitPython on PiPicoMite0x Cards

• Reduced parts count for CircuitPython

• The PiPicoMite0x cards can run CircuitPython with some limitations
• Card features for CircuitPython application
  • SD support
  • (2) MCP23017, 16-bit port expanders for 32-bits of Digital I/O
    • DB-37
  • 5V input
  • External I2C on J1
  • (2) 1x20 headers breakout all Pico pins
• CircuitPython does not have built-in support for
  • VGA
  • PS/2
  • Audio

CircuitPython Digital I/O

• PiPicoMite02_Digio32.py - Library
  • Control the (2) MCP23017 parts on the PiPicoMite02
  • Provides Arduino-like functions

# digitalWrite(bit,value)
#    bit = 0-31
#    value = 0, 1
# digitalRead(bit)
#    bit = 0-31
#    returns 0, 1
# pinMode(bit,value)
#    bit = 0-31
#    value = INPUT, OUTPUT, INPUT_PULLUP
# pinMode(bit,value)

• Digio32Test.py - Example code uses the PiPicoMite02_Digio32 library

CircuitPython SD Card

• Adafruit CircuitPython Module Install
• Code Storage on SD Card
• SDCard_Dir.py - List SD Card directory
• Pins

# CS = GP13
# SCK = GP10
# MOSI = GP11
# MISO = GP12

spi = busio.SPI(board.GP10, MOSI=board.GP11, MISO=board.GP12)
cs = board.GP13

sdcard = sdcardio.SDCard(spi, cs)

• Make directories

>>> os.mkdir('/sd/CircuitPython/')
>>> os.mkdir('/sd/CircuitPython/SD_Card')

• Add code to path

>>> import sys
>>> sys.path
['', '/', '.frozen', '/lib']
>>> sys.path.append("/sd")
>>> sys.path
['', '/', '.frozen', '/lib', '/sd']
>>> os.listdir('/sd/CircuitPython/SD_Card')
[]

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
• If optional port expander is installed
  • LED-32 card
  • Cable from GPIO to LED-32 card

Test SD card interface

• Type

files

• Returns

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

Test Sound

• 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 GPIO (optional (2) MCP23017 are installed)

• GPIO32-01.bas - Test program
• Connect LED-32 card to P1 via DB37RIBBON card and cable
• Type

> chdir "/lbcards/GPIO32"
>load "GPIO32-01.bas"
>run
Looping through LEDs
Hit a key to stop

• LEDs will blink
• Any key will stop the program

flash save 3

PiPicoMite02 P1 to LED-32 wiring

• PiPicoMite02 P1 is a female connector
• Use DB37RIBBON to convert to right angle header pins
• LED-32 has a 40-pin right angle header pins
• Cable has (2) of 2x10 Dupont housings at each end
• Wiring

P1	Chip	Port	Bit	DB37RIB	LED	LED-32 pin	Color		P1	Chip	Port	Bit	DB37RIB	LED	LED-32 pin	Color
1			GND	1		39	BLK		20			GND	2		40	BLK
2	0	B	7	3	D15	35	WHT		21	0	A	0	4	D31	36	BRN
3	0	B	6	5	D14	33	GRY		22	0	A	1	6	D30	34	ORA
4	0	B	5	7	D13	31	VIO		23	0	A	2	8	D29	32	YEL
5	0	B	4	9	D12	29	BLU		24	0	A	3	10	D28	30	GRN
6	0	B	3	11	D11	27	GRN		25	0	A	4	12	D27	28	BLU
7	0	B	2	13	D10	25	YEL		26	0	A	5	14	D26	26	VIO
8	0	B	1	15	D9	23	ORA		27	0	A	6	16	D25	24	GRY
9	0	B	0	17	D8	21	BRN		28	0	A	7	18	D24	22	WHT
10			N/C	19					29	1	B	7	20	D23	20	WHT
11	1	A	0	21	D0	5	BRN		30	1	B	6	22	D22	18	GRY
12	1	A	1	23	D1	7	ORA		31	1	B	5	24	D21	16	VIO
13	1	A	2	25	D2	9	YEL		32	1	B	4	26	D20	14	BLU
14	1	A	3	27	D3	11	GRN		33	1	B	3	28	D19	12	GRN
15	1	A	4	29	D4	13	BLU		34	1	B	2	30	D18	10	YEL
16	1	A	5	31	D5	15	VIO		35	1	B	1	32	D17	8	ORA
17	1	A	6	33	D6	17	GRY		36	1	B	0	34	D16	6	BRN
18	1	A	7	35	D7	19	WHT		37			+3.3V	36	D15
19			+3.3V	37

Test 5V in

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

Test I2C header (RTC)

• Use DS1307 RTC (ebay search) attached to I2C J1

1. J1 I2C0SCL wired to RTC SCL
2. J1 I2C0SDA wired to RTC SDA
3. J1 VCC wired to RTC VCC
4. J1 GND wired to RTC GND

• If RTC is not configured, type

option system i2c gp0, gp1
rtc settime YYYY, MM, DD, HH, MM, SS

• Check time

rtc gettime
print time$

• Verify RTC time works

Combined Copy/Paste

• Above tests can be copy/pasted

files

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

play stop

chdir "/demos"
load "Colours.bas"

mode 1

option system i2c gp0, gp1
rtc gettime
print time$

SPI port expanders

• Experimental - Untested

It seems to me that the GP2-GP5 lines could be used for SPI since they are on SPI0. The other SPI bus connects to the SD card socket using SPI1 so there should be no conflict with the port use. I’m not sure about software implementation/support in the MMBASIC since I’ve not tried it.

Looks like the SPI connections would be:

• GP2/SPI0-SCK MCP23S17 Pin 12, Pico Pin 4
• GP3/SPI0-MOSI MCP23S17 Pin 13, Pico Pin 5
• GP4/SPI0-MISO MCP23S17 Pin 14, Pico Pin 6
• GP5/SPI0-CS MCP23S17 Pin 11, Pico Pin 7

Mechanicals

Issues

Rev 1

• No issues

Assembly Sheet

• PiPicoMite02 Rev1 Assembly Sheet
• Interactive BOM