PiPicoMite01

Features

• Raspberry Pi Pico
  • All pins brought to header
  • Pin marking on rear
• VGA (1:2:1 - R:G:B) - 16 colors
• 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
• Stereo audio
  • 3.5mm jack
• 16-bit GPIO
  • MCP23017 port expander
  • I2C1
  • 2x10 0.1" pitch header
  • Jumper selectable terminators
• Power options
  • 5V power input via USB B or 0.1" pitch header
  • 3.3V output header
• 120mmx70mm outline
• (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. 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.

Pin Marking on Rear

Schematic

• PiPicoMite01 Rev 1 Schematic

Connectors

H1 - 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

J1 - I2C Interrupt

• Install jumper to connect INTA interrupt from MCP23008 to GP0

J2 - USB B Power Connectors

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

J3/J5 Pico Connectors

GP	FUNCTION	PICO PIN
GP6	AUDIO-L	9
GP7	AUDIO-R	10
GND	AUDIO-GND	8
3.3V	PS2_3.3V
VSYS	PS2_5V	39
GP8	PS2_CLK	11
GP9	PS2_DATA	12
GND	PS2_GND	13
3.3V	SD_3.3V
GP12	SD_MISO	16
GP11	SD_MOSI	15
GP10	SD_SCK	14
GP13	SD_SLVSEL	17
GND	SD_GND	18
GP18	VGA_BLU	24
GND	VGA_GND	23
GP20	VGA_GRN_HI	26
GP19	VGA_GRN_LO	25
GP16	VGA_HSYNC	21
GP21	VGA_RED	27
GP17	VGA_VSYNC	22

J4 - 5V Input

• Useful for external 5V

J6 - 3.3V Power Out

J7 - Audio

• PLAY WAV "file.wav"

J8 - PS/2 Keyboard

J9 - GPIO

• Install jumper to connect Interrupt from MCP23017 to GP0 pin on Pico
• No Pull-up

J10 - 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.

SD1 - SD Card

Prototype Build

• Runs PicoMite (MaxiMite) BASIC (VGA, PS/2)
• Uses cards
  • Raspberry Pico on Breadboard
  • VGAX49
  • PS2X49
  • SD CARD X49
  • GRID49
• Pinouts

Configuration

OPTION KEYBOARD US
OPTION DISPLAY 20, 40
OPTION SDCARD GP13, GP10, GP11, GP12
OPTION AUDIO GP6,GP7, ON PWM CHANNEL 3

Raspberry Pi Pico in a Small Plastic Project Box

• Raspberry Pico on Breadboard

VGAX49

• VGAX49
• Resistors Values
  • Selected for 0.7V output on analog RGB pins
  • R12 = 270
  • R6 = 390
  • R7 = 820
  • R1 = 270

	R,B		G RES		G
Rs	75		R1	390	75
Rm	270		R2	820	264.298
Vin	3.3		RM	264.298	3.3
Vout	0.717				0.729
I (mA)	9.57		I (mA)		9.73

PS2X49

• PS2X49
• PWR1 is the power to the PS/2 #1, #2 connectors (5V)
• +3.3V powers the TXS0104 translator
• Routing
  • CLK1, DAT1 on J3 go to J1 (Purple)
  • CLK2, DAT2 on J3 go to J2 (Not used)

SD CARD X49

• SD CARD X49
• Install NO5V jumper
• Connect 3.3V power
• No 5V attached
• No U2 voltage regulator needed

GRID49 - Audio Filter

• GRID49
• Audio filter circuit

• C1 = Audio_In-L
• D1 - GND
• E1 - Audio_In-R

Cabling

FUNCTION	GP	PICO PIN	CARD	SIG	PIN	COLOUR
AUDIO-GND	GND	8	GRID49	AUD-GND	D1	BLK
AUDIO-L	GP6	9	GRID49	AUD-L	C1	VIO
AUDIO-R	GP7	10	GRID49	AUD-R	E1	YEL
PS2_CLK	GP8	11	PS2X49	CLK1	6	VIO
PS2_DATA	GP9	12	PS2X49	DAT1	8	YEL
PS2_GND	GND	13	PS2X49	GND	10	BLK
SD_SCK	GP10	14	SD_CARD_X49	SCLK	3	VIO
SD_MOSI	GP11	15	SD_CARD_X49	MOSI	4	BLU
SD_MISO	GP12	16	SD_CARD_X49	MISO	2	YEL
SD_SLVSEL	GP13	17	SD_CARD_X49	-SDCS	5	GRY
SD_GND	GND	18	SD_CARD_X49	GND	1	BLK
VGA_HSYNC	GP16	21	VGA	HS	17	GRY
VGA_VSYNC	GP17	22	VGA	VS	18	WHT
VGA_GND	GND	23	VGA	GND	19	BRN
VGA_BLU	GP18	24	VGA	B4	12	BLU
VGA_GRN_LO	GP19	25	VGA	G4	7	GRN
VGA_GRN_HI	GP20	26	VGA	G5	6	GRN
VGA_RED	GP21	27	VGA	R4	1	ORG
PS2_5V	VSYS	39	PS2X49	PWR1	2	ORG
PS2_3.3V	3.3V	BUS	PS2X49	3.3V	4	RED
SD_3.3V	3.3V	BUS	SD_CARD_X49	3.3V	7	RED

Mechanicals

Applications

Tetris

> memory
Program:
  13K (10%) Program (485 lines)
  95K (90%) Free

RAM:
   8K ( 5%) 31 Variables
   0K ( 0%) General
 132K (95%) Free

Issues

Rev 1

• SDA, SCL swapped to MCP23017
• Cut etch solder side U2-12
• Cut etch solder side U2-13
• Add wire Pico pin 19 to U2-13 (GP14) (or etch that went to Pico pin 20)
• Add wire Pico pin 20 to U2-12 (GP15) (or etch that went to Pico pin 19)

Assembly Sheet

• PicoMite01 Rev1 Assembly Sheet