General • Re: any existing high-speed pico-to-pico bus?

Code:

from   machine import Pinfrom   rp2     import asm_pio, PIO, StateMachineimport time# High-Speed '32N1' UART-style serial transfer# The minimum number of PIO cycles per bit is in effect 3. No matter if we# catch the falling edge of the start bit early in a cycle or late then we# should still sample a valid bit. And, after the last bit, should be back# in the stop bit ready for the next falling edge.#         Start        Lsb                     Msb        Stop#  ---.   .   .   .---.---.---.---.---.---.---.---.---.---.---.---.#     |___.___.___|___.___.___|___.___.___|___.___.___|           |___.___##     |-------------->|---------->|           |---------->|#         |-------------->|---------->|           |---------->|# We use UART polarity of Idle High and Start Bit Low so it is compatible# with any hardware drivers intended for UART use. We also send Lsb first# and Msb last so the PIO code will work with fewer than 32 bits.# .-------------------------------------------------------------------------.# |     Define configuration                                                |# `-------------------------------------------------------------------------'# Use same pin for input and output for zero-linking testingTX_PIN = 0RX_PIN = TX_PIN# .-------------------------------------------------------------------------.# |     Define operating speed, maximum baud rate                           |# `-------------------------------------------------------------------------'machine.freq(240_000_000)HZ        = machine.freq()BAUD_RATE = HZ // 3def Show(n, u) :  return "{:>11,} {:<3} - {:5.1f} M{}".format(n, u, n / 1_000_000, u)  print("Operating speed : {}".format(Show(HZ, "Hz")))print("Transfer rate   : {}".format(Show(BAUD_RATE, "bps")))# .-------------------------------------------------------------------------.# |     Serial transmission                                                 |# `-------------------------------------------------------------------------'@asm_pio(sideset_init = PIO.OUT_HIGH,         out_init     = PIO.OUT_HIGH,         out_shiftdir = PIO.SHIFT_RIGHT,         fifo_join    = PIO.JOIN_TX)def TxPio(BITS=32):                     #                        _____                                        #                       |     |    pull()              .side(1) [2]    # --.--               --^--   |                                        #   | 3                       |    set(x, BITS-1)      .side(0) [2]    # --.--     _____             | 3    label("tx_loop")                    #   | 3    |     |            |    out(pins, 1)                        # --^--  --.--   | 3  --.--   |    jmp(x_dec, "tx_loop")        [1]    #          |_____|      |_____|# .-------------------------------------------------------------------------.# |     Serial reception                                                    |# `-------------------------------------------------------------------------'@asm_pio(set_init    = PIO.IN_LOW,         in_shiftdir = PIO.SHIFT_RIGHT,         fifo_join   = PIO.JOIN_RX)def RxPio(BITS=32):                     #                        _____                                        #                       |     |    wait(0, pin, 0)                     # --.--               --^--   |    set(x, BITS-1)              [1]     #   |                         |    label("rx_loop")                    #   | 4     _____             | 3    nop()                               #   |      |     |            |    in_(pins, 1)                        # --^--  --.--   | 3  --.--   |    jmp(x_dec, "rx_loop")               #          |_____|      |     |    push()                              #                       |_____|# .-------------------------------------------------------------------------.# |     Initialise serial loop-back                                         |# `-------------------------------------------------------------------------'# Need to initialise RX first to handle using same pin for TXrxPin = Pin(RX_PIN, Pin.IN, Pin.PULL_UP)rx = StateMachine(1, RxPio,                     freq         = BAUD_RATE * 3,                     in_base      = rxPin)txPin = Pin(TX_PIN, Pin.OUT, value=1)tx = StateMachine(0, TxPio,                     freq         = BAUD_RATE * 3,                     sideset_base = txPin,                     out_base     = txPin)# .-------------------------------------------------------------------------.# |     Test loop-back                                                      |# `-------------------------------------------------------------------------'n = 0while True:  # Slow things down so we get a chance to see what's happening  time.sleep(1)  print("")  # Freeze TX so everything goes out as fast as possible as a burst  tx.active(0)  for k in range(8):    tx.put(1 << n)    n = (n + 1) & 31  # Enable RX and then enable TX to send data out as a burst  rx.active(1)  tx.active(1)  while rx.rx_fifo():    print("{:08X}".format(rx.get()))

Code:

pi@Pi3B:~/pico/micropython/ports/picopython/modules-examples $ mptool run HighSpeedPioUart.pyExecuting 'HighSpeedPioUart.py' on the deviceOperating speed : 240,000,000 Hz  - 240.0 MHzTransfer rate   :  80,000,000 bps -  80.0 Mbps0000000100000002000000040000000800000010000000200000004000000080etc