from machine import Pin
from rp2 import PIO, StateMachine, asm_pio

# Constants
UART_BAUD = 9600          # UART baud rate
PIN_BASE = 10             # Starting pin number
NUM_UARTS = 8             # Number of UART TXs

# PIO program for UART TX
@asm_pio(sideset_init=PIO.OUT_HIGH, out_init=PIO.OUT_HIGH, out_shiftdir=PIO.SHIFT_RIGHT)
def uart_tx():
    pull()                            # Wait for data in TX FIFO
    set(x, 7) .side(0)       [7]      # Start bit (LOW for 8 cycles)
    label("bitloop")
    out(pins, 1)            [6]       # Shift out 8 data bits, each bit lasts 8 cycles
    jmp(x_dec, "bitloop")             # Decrement bit counter, loop until done
    nop()      .side(1)       [6]     # Stop bit (HIGH for 8 cycles)

# Initialize 8 UART TXs on pins 10 to 17
uarts = []
for i in range(NUM_UARTS):
    sm = StateMachine(
        i, uart_tx, freq=8 * UART_BAUD, 
        sideset_base=Pin(PIN_BASE + i), 
        out_base=Pin(PIN_BASE + i)
    )
    sm.active(1)
    uarts.append(sm)

# Function to send a string over a specific State Machine
def pio_uart_print(sm, s):
    for c in s:
        while sm.tx_fifo() >= 4:  # Wait if the FIFO is full
            pass
        sm.put(ord(c))  # Send ASCII value of each character

# Send "hello" 100 times on all 8 UART TX lines
for _ in range(100):  # Repeat 100 times
    for u in uarts:   # Send through all UARTs
        pio_uart_print(u, "hello\n")