Upload New File

This commit is contained in:
Valerie Sireneva 2023-10-18 14:38:11 +00:00
parent e23c7ef39d
commit 8c69924afa

View file

@ -0,0 +1,92 @@
'''
Circuit Python wrapper around PIO implementation of UART
Original source of these examples: https://github.com/adafruit/Adafruit_CircuitPython_PIOASM/tree/main/examples (MIT)
'''
import rp2pio
from array import array
'''
.program uart_tx
.side_set 1 opt
; An 8n1 UART transmit program.
; OUT pin 0 and side-set pin 0 are both mapped to UART TX pin.
pull side 1 [7] ; Assert stop bit, or stall with line in idle state
set x, 7 side 0 [7] ; Preload bit counter, assert start bit for 8 clocks
bitloop: ; This loop will run 8 times (8n1 UART)
out pins, 1 ; Shift 1 bit from OSR to the first OUT pin
jmp x-- bitloop [6] ; Each loop iteration is 8 cycles.
; compiles to:
'''
tx_code = array('H', [40864, 63271, 24577, 1602])
'''
.program uart_rx_mini
; Minimum viable 8n1 UART receiver. Wait for the start bit, then sample 8 bits
; with the correct timing.
; IN pin 0 is mapped to the GPIO used as UART RX.
; Autopush must be enabled, with a threshold of 8.
wait 0 pin 0 ; Wait for start bit
set x, 7 [10] ; Preload bit counter, delay until eye of first data bit
bitloop: ; Loop 8 times
in pins, 1 ; Sample data
jmp x-- bitloop [6] ; Each iteration is 8 cycles
; compiles to:
'''
rx_code = array('H', [8224, 59943, 16385, 1602])
class PIO_UART:
def __init__(self, *, tx, rx, baudrate=9600):
if tx:
self.tx_pio = rp2pio.StateMachine(
tx_code,
first_out_pin=tx,
first_sideset_pin=tx,
frequency=8 * baudrate,
initial_sideset_pin_state=1,
initial_sideset_pin_direction=1,
initial_out_pin_state=1,
initial_out_pin_direction=1,
sideset_enable=True,
)
if rx:
self.rx_pio = rp2pio.StateMachine(
rx_code,
first_in_pin=rx,
frequency=8 * baudrate,
auto_push=True,
push_threshold=8,
)
@property
def timeout(self):
return 0
@property
def baudrate(self):
return self.tx_pio.frequency // 8
@baudrate.setter
def baudrate(self, frequency):
self.tx_pio.frequency = frequency * 8
self.rx_pio.frequency = frequency * 8
def write(self, buf):
return self.tx_pio.write(buf)
@property
def in_waiting(self):
return self.rx_pio.in_waiting
def read(self, n):
b = bytearray(n)
n = self.rx_pio.readinto(b)
return b[:n]
def readinto(self, buf):
return self.rx_pio.readinto(buf)