MMBASIC on XIAO RP2040

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Overview[edit]

  • Card set running BASIC Interpreter for the Raspberry Pi Pico on Seeed Studio XIAO RP2040
  • MMBasic is a Microsoft BASIC compatible implementation of the BASIC language with floating point, integer and string variables, arrays, long variable names, a built in program editor and many other features
  • 8 Flash locations for storage.
  • Support for SD Card

MMBASIC Credits[edit]

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.

Hardware[edit]

Seeed Studio XIAO RP2040[edit]

XIAO-RP2040.PNG

QT_Py_(RP2040_based) Wiki page

  • Two manufacturers
  • USB Type C connector
  • RP2040 32-bit Cortex M0+ dual-core
  • Runs at ~125 MHz
  • 264 KB RAM
  • SPI FLASH chip for storing files and CircuitPython/MicroPython code storage
    • 8 MB - Adafruit
    • 2 MB - Seeedstudio
  • No EEPROM
  • Can be used with C/C++ (Arduino), MicroPython, or CircuitPython
  • Built-in RGB NeoPixel LED
  • 13 GPIO pins (11 breakout pads and two QT pads):
    • Four 12 bit ADCs (one more than Pico)
    • I2C port
      • 2 I2C: 1 on QT pins, one on the (Adafruit) breakout pads - Adafruit
      • 1 I2C on XAIO
    • SPI and UART peripherals, in standard QT Py locations,
    • PWM outputs on every IO pin - for servos, LEDs, etc
    • There are 6 GPIO in consecutive order for PIO compatibility
  • 3.3V logic and power 600 mA
  • Both Reset button and Bootloader select buttons for quick restarts (no unplugging-replugging to relaunch code)

QTPy49-01 Card[edit]

QTPy49-01-P1080524-720px.jpg

  • The QTPy49-01 Card combines the QTPy49 card and SD_CARD_X49 card onto one card
  • Headers for other pins
  • DC in jack with 5V regulator and Schottky diode
  • Power can be supplied from DC in (7-12V) or USB Jack

QTPy49 / SD Card Set[edit]

QTPY49 MMBASIC P18420-720pxV.jpg

QTPy49 breakout card[edit]

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QTPy49 Wiki page

  • QT Py (RP2040 based) CPU choices are
  • Connectors/Headers
    • DC Power
    • AD0 GVS
    • AD1 GVS
    • AD2 GVS
    • AD3 GVS
    • I2C with ground/VCC
    • TX/RX with ground/VCC
    • SPI with ground/VCC
  • QTPy49 can be powered from with either the USB C or DC jack
    • Automatic Schottky diode power switching between
      • 5V from USB C
      • 5V on external DC jack
      • 7-12V on DC jack
  • 49x49mm ODAS form factor
  • (4) 4-40 mounting holes

SD Card[edit]

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SD_CARD_X49 wiki page

  • SD or SDHC card adapter
  • 5V to 3.3V regulator
  • 3.3V to 5V TXS0104E level shifter
  • Activity LED
  • 49 x 49 mm ODAS foprm factor
  • (4) 4-40 mounting holes

SD Card Wiring[edit]

Signal SD_CARD_X49 QTPy49 conn QTPy GP PiPico Pin
SPI_SCLK J1-3 J3-6 GP2 GPIO2
SPI_MOSI J1-4 J3-4 GP3 GPIO3
SPI_MISO J1-2 J3-5 GP4 GPIO4
SPI_SS J1-5 J9-3 GP26 GPIO26
GND J1-1 J9-1 GND GND
VCC (3.3V) J1-7 J9-2 VCC VCC

SD Configuration[edit]

OPTION SYSTEM SPI GP2, GP3, GP4
OPTION SDCARD GP26
OPTION COLOURCODE ON

  • Verify it is working
> FILES
A:/
   <DIR>  basic
   <DIR>  bmps
   <DIR>  demos
   <DIR>  games
   <DIR>  jpegs
   <DIR>  lbcards
   <DIR>  performance
   <DIR>  wave
8 directories, 0 files

RS-232 (option)[edit]

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DTE wiki page

  • TTL to RS-232 converter
  • Male DB-9 connector
  • FTDI pinout (reversed directions to directly connect to FTDI Interface)
  • 49x49mm card
  • 4x 4-40 holes
  • DTE card

Command to use serial as console[edit]

  • 115,200 baud = default
OPTION SERIAL CONSOLE GP1, GP0

  • Command to use serial as console switch back from the serial port to the USB on the XIAO RP2040
option serial console disable

User Serial port[edit]

  • Command to use serial as COM port
setpin gp1,gp0, com1
open "com1:9600" as #5
print #5, "Hello"

RS-232 Wiring[edit]

  • Wiring to DTE card
DTE signal DTE pin QTPy GP PiPico Pin
GND H1-1 GND J4-1
CTS H1-2 N/C N/C
VCC H1-3 VCC J4-2
TX H1-4 TX_D6 J4-3
RX H1-5 RX_D7 J4-4
RTS H1-6 N/C N/C

RS-232 Stackup[edit]

QTPy49-01 P18561 720px.jpg

QTPy49 MMBASIC P1080442-720px.jpg

RS-232 to USB[edit]

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  • Uses FTDI-49MM FTDI to TTL card
  • RS-232 to USB
  • Mates to CPU stackup

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  • Brought all the way back to USB

QTPy49 MMBASIC P18445-720px.jpg

MMBASIC Card Stack-up[edit]

QTPY49 MMBASIC P18420-720pxV.jpg

Software[edit]

Install MMBASIC on Seeed XIAO RP2040[edit]

  • Hold down the "BOOT" button
    • The "B" is written on the board shown to the right
  • Connect the XIAO RP2040 via USB C cable to your computer while still pressing the button
  • The computer then will appear a disk driver(RP1-RP2)
  • Download the PicoMite_Firmware.zip
  • Drag the .uf2 file to the disk drive ("RP1-RP2")
  • Card will re-boot
  • Connect in TeraTerm over serial

MMBASIC Free Memory[edit]

  • V5.070501
> print mm.ver
 5.0704
> memory
Program:
   0K ( 0%) Program (0 lines)
 124K (100%) Free

RAM:
   0K ( 0%) 0 Variables
   0K ( 0%) General
 156K (100%) Free

GPIO from MMBASIC[edit]

QTPy49 Marking GPIO
A0 GP26 (SD_SS)
A1 GP27
A2 GP28
A3 GP29
I2C_SDA GP6
I2C_SCL GP7
RX GP1
TX GP0

MMBASIC - Using Pins[edit]

  • Digital I/O
SETPIN GP27, DIN:' Digital Input
SETPIN GP28, DOUT:' Digital Output
PIN(GP28) = 1:'Digital output

  • Analog Input
SETPIN GP29, AIN:' Analog Input

  • SETPIN(s) for Serial and I2C
SETPIN GP1, GP0, COM1
SETPIN GP6, GP7 I2C2

On-Board LED[edit]

  • No Built-in support in MMBASIC for the on-board NEOPIXEL
  • Red, Green, Blue LED
  • Pull Low to turn on RGB LED bits
  • At-boot - RGB LED blinks Cyan/Green by MMBASIC
  • Red LED = GP17
  • Green LED = GP16
  • Blue LED = GP25 (Used by MMBASIC)
' Make pins outputs
SETPIN GP17, DOUT:' Red LED
SETPIN GP16, DOUT:' Green LED
SETPIN GP25, DOUT:' Blue LED
' Turn off LEDS
PIN(GP17)=1:' Turn off Red LED
PIN(GP25)=1:' Turn off Blue LED
PIN(GP16)=1:' Turn off Green LED
' Turn on LEDs
PIN(GP17)=0:' Turn on Red LED
PIN(GP25)=0:' Turn on Blue LED
PIN(GP16)=0:' Turn on Green LED

Demo Code[edit]