Complete P2 assembly-language synchronous receiver-transmitter code
JonTitus
Posts: 193
I hope this example might help. A large thank you to Forum members who helped. --Jon
' Synchronous serial transmission, Rev. 3, 06-13-2020 at 1007 MDT
'positive edge-trigger (Jon Titus)
CON
clkout = 40 ' Pin P40 'Transmitter's clock out, to P31
txout = 41 ' Pin P41 'Transmitter data out, to P30
rxin = 30 ' Pin P30 'Receiver data in
rxclkin = 31 ' Pin P31 'Receiver clock in
'Remember to connect these pins as noted!
dat
org 0
coginit id, ##@sync_receive ' Initialize an available cog for sync receive
'====================================
' Sync-serial transmit of data at set intervals.
dirl #txout 'Transmitter setup
wrpin sync_tx_mode, #txout 'Set sync tx mode for pin 41
wxpin #%1_00111, #txout 'Set up stop/start mode, X[5] = 1, 8 bits (7 + 1)
dirh #txout 'Enable transmitter output
dirl #clkout 'Clock output setup
wrpin clock_mode, #clkout 'Set pin as transition-output mode
wxpin ##$1000, #clkout 'Set base period for transition output
dirh #clkout 'Enable clock-output
.loop waitx ##10_000_000 'Delay between transmissions
wypin ##$11, #txout '8-bit data to transmit, your choice
wypin #16, #clkout 'Start clock, transmit data
jmp #.loop 'Continue to transmit
sync_tx_mode long %0000_1111_000_0000000000000_01_11100_0 'Positive-edge clock mode
clock_mode long %0000_0000_000_000000_0_000000_01_00101_0 'Clock-mode
id long 16 'Need the variable, but not used
'====================================
' Sync-serial receive, data to 8 LEDs on P7-P0
' This software runs in a separate cog
org 0
sync_receive mov dira, ##$00FF 'Pins P7--P0 set as outputs
dirl #rxin 'Reset receiver Smart Pin
wrpin sync_rx_mode, #rxin 'Set sync receiver mode
wxpin #%1_00111, #rxin 'Set receiver to sample on B-input edge
dirh #rxin 'Enable Smart-Pin sync receiver
.test_loop testp #rxin wc 'Wait in loop for received data; IN flag raised
nop
if_nc jmp #.test_loop 'If no C flag, repeat testing
rqpin rcvd_data, #rxin 'Put 32-bit data (see text) in rcvd_data
shr rcvd_data, #24 'shift-right data 24 places to LSB
mov outa, rcvd_data 'Send 8 bit data to LEDs
jmp #.test_loop 'Continue to receive and display data
sync_rx_mode long %0000_0001_000_0000000000000_01_11101_0
rcvd_data long $00
Comments
I'm assuming you have the unnecessary nop inside .test_loop to save some power while waiting. If you really want to save power, you can entirely avoid the busy-wait loop using SETSE1/2/3/4 and WAITSE1/2/3, or SETPAT and WAITPAT.
Is there any reason you used RQPIN and not RDPIN? I've never used RQPIN; I was under the impression that you normally only ever use RQPIN instead of RDPIN if you AKPIN or RDPIN that it somewhere else.
Sandy