Cardputer adv keyboard support

[TheMongoose]

Hi there!

I am currently working on a circuit python project with the cardputer adv! While the screen may work, the keyboard does not. I learned that the keyboard type is the TCA8418RTWR. I was wondering if someone could help add support to it, or make python code to give it support.

Thank you!

[dhalbert]

#10757 is related, but does not solve your problem.

[dglaude]

In short there is a TCA8418 (python) library for CP: https://docs.circuitpython.org/projects/tca8418/en/latest/

So if you free the pins (with current firmware they blocked by the keyboard scanning code for the v1 cardputer) to reuse them for I2C... then it should be possible to communicate with the TCA8418 and use it in keyboard scanning mode (see this learn guide for an Adafruit product based on TCA8418: https://learn.adafruit.com/adafruit-tca8418-keypad-matrix-and-gpio-expander-breakout).

I have no success yet, but this could let you get keyboard input within your Python code, but it does not make the keyboard work in the REPL (like it does for the old cardputer v1 and v1.1). Compiling your own firmware with #10757 (or just downloading the artifact generated by the github action) will bring you a firmware that initiate the screen, but does not lock the GPIO that you need for I2C.

The next level will be to develop C code to do the TCA8418 scanning in a CP firmware dedicated for the Cardputer ADV.

[TheMongoose]

I have almost got it to work, for a little while at least. For some reason it stopped working and refused to take input, what you have to do is use the m5stamp circutpython system instead so that it can run those pins.

[TheMongoose]

I have gotten it to work! After hours of debugging.

here is the code

import time
import board
import busio
import digitalio
import microcontroller
import displayio
import terminalio
from adafruit_display_text import label

# --- 1. DISPLAY SETUP ---
displayio.release_displays()

# Force Backlight On
try:
    bl = digitalio.DigitalInOut(microcontroller.pin.GPIO38)
    bl.direction = digitalio.Direction.OUTPUT
    bl.value = True
except: pass

# SPI Init
spi = busio.SPI(clock=microcontroller.pin.GPIO36, MOSI=microcontroller.pin.GPIO35)

# Init Driver (ST7789)
try:
    # Try CircuitPython 9.x style
    from fourwire import FourWire
    display_bus = FourWire(spi, command=microcontroller.pin.GPIO34, chip_select=microcontroller.pin.GPIO37, reset=microcontroller.pin.GPIO33)
except ImportError:
    # Try CircuitPython 8.x style
    display_bus = displayio.FourWire(spi, command=microcontroller.pin.GPIO34, chip_select=microcontroller.pin.GPIO37, reset=microcontroller.pin.GPIO33)

from adafruit_st7789 import ST7789
display = ST7789(display_bus, rotation=270, width=240, height=135, rowstart=40, colstart=53)

# UI Groups
splash = displayio.Group()
display.root_group = splash
bg_bitmap = displayio.Bitmap(240, 135, 1)
bg_palette = displayio.Palette(1)
bg_palette[0] = 0x000000
splash.append(displayio.TileGrid(bg_bitmap, pixel_shader=bg_palette, x=0, y=0))

# Text Labels
title = label.Label(terminalio.FONT, text="CARDPUTER ADV", color=0x00FFFF, x=5, y=15, scale=2)
status = label.Label(terminalio.FONT, text="Initializing...", color=0xFFFFFF, x=5, y=50, scale=2)
key_debug = label.Label(terminalio.FONT, text="WAITING...", color=0x00FF00, x=5, y=90, scale=2)

splash.append(title)
splash.append(status)
splash.append(key_debug)

# --- 2. KEYBOARD HARDWARE SETUP ---
# Interrupt Pin (The Heartbeat)
irq_pin = digitalio.DigitalInOut(board.IO44)
irq_pin.direction = digitalio.Direction.INPUT
irq_pin.pull = digitalio.Pull.UP

# Main Bus (Shared with Power Chip)
i2c = busio.I2C(board.IO9, board.IO8)

# --- 3. BLIND CONFIGURATION ---
# We write raw bytes to 0x34 to force the TCA8418 into scanning mode.
# We ignore errors because the Power Chip might "NACK" us, but the Keyboard listens.

def write_reg(addr, reg, val):
    while not i2c.try_lock(): pass
    try:
        i2c.writeto(addr, bytes([reg, val]))
    except:
        pass # Ignore conflict errors
    i2c.unlock()

status.text = "CONFIGURING..."
try:
    # 1. Wake Power Chip (Ensure voltage is stable)
    write_reg(0x34, 0x92, 0xFF) # ALDOs
    
    # 2. Configure TCA8418 (Keyboard)
    # Enable Rows 0-7
    write_reg(0x34, 0x1D, 0xFF) 
    # Enable Cols 0-7
    write_reg(0x34, 0x1E, 0xFF) 
    # Enable Cols 8-9
    write_reg(0x34, 0x1F, 0x03) 
    # Enable Interrupts + Keypad Mode
    write_reg(0x34, 0x01, 0x11)
    
    status.text = "SYSTEM READY"
    status.color = 0x00FF00
except Exception as e:
    status.text = "SETUP ERROR"
    key_debug.text = str(e)[:15]

# --- 4. MAIN LOOP ---
print("Starting Input Loop...")

last_key_time = 0

while True:
    # Wait for Interrupt (Low)
    if irq_pin.value == False:
        # Debounce (prevent double reading)
        if time.monotonic() - last_key_time > 0.1:
            while not i2c.try_lock(): pass
            
            try:
                # Read Key Event Register (0x04)
                buf = bytearray(1)
                i2c.writeto_then_readfrom(0x34, bytes([0x04]), buf)
                val = buf[0]
                
                # Check if it's a valid key press (Bit 7 is set for Press, clear for Release)
                # 0xC4 = 11000100 -> Key ID 68 Pressed
                if val > 0:
                    key_id = val & 0x7F
                    is_pressed = (val & 0x80) > 0
                    
                    if is_pressed:
                        key_debug.text = f"KEY ID: {key_id}"
                        print(f"Key Pressed: {key_id}")
                    
                    # Clear Interrupt (Write 1 to Reg 0x02, Bit 0)
                    # Necessary to reset the IO44 pin to HIGH
                    i2c.writeto(0x34, bytes([0x02, 0x01]))
                    
                    last_key_time = time.monotonic()
                    
            except Exception as e:
                print("Read Error (Collision)")
                
            i2c.unlock()
            
    # Small sleep to save battery
    time.sleep(0.01)

[TheMongoose]

Thank you all for your help!

[TheMongoose]

I hope this can be used to improve circuit python for everyone! And I am sure this will contribute to the m5 community!