92 lines
2.7 KiB
Plaintext
92 lines
2.7 KiB
Plaintext
// Raspberry Pi Pico PIO program to output data to a TFT
|
|
// controller via a 8 bit 8080 style data path.
|
|
|
|
// Original sourced from:
|
|
// https://github.com/zapta/pio_tft
|
|
|
|
// Side set: 1 output pin, TFT_WR. Active low.
|
|
// Data set: 8 consecutive output pins, TFT_D0 .. TFT_D7
|
|
|
|
.program tft_io
|
|
.side_set 1 opt ; The TFT_WR output.
|
|
|
|
// The C++ code switches between the different SM routines
|
|
// by waiting for the SM to be idle and setting its PC.
|
|
// The default SM routine is a 16 bit transfer
|
|
|
|
// Do a block fill of N+1 pixels.
|
|
public block_fill:
|
|
// Fetch colour value.
|
|
pull side 1
|
|
// Move colour to x.
|
|
mov x, osr
|
|
// Fetch pixel count N (sends N+1 pixels).
|
|
pull
|
|
// Move pixel count to y.
|
|
mov y, osr
|
|
next:
|
|
// Copy colour value into osr, colour in LS 16 bits.
|
|
mov osr, x side 1
|
|
// Output colour 8 MS bits, unwanted top 16 bits shifted through.
|
|
out pins, 24 side 0 [1]
|
|
// Write first colour byte.
|
|
nop side 1 [1]
|
|
// Write second colour byte.
|
|
out pins, 8 side 0 [1]
|
|
// Decrement pixel count and loop.
|
|
jmp y--, next side 1
|
|
|
|
.wrap_target
|
|
// Transmit a 16 bit value (LS 16 bits of 32 bits).
|
|
public start_tx:
|
|
// Fetch the next 32 bit value from the TX FIFO and set TFT_WR high.
|
|
pull side 1
|
|
// Write the first byte (MSB) and set WR low. This also
|
|
// shifts the unused top 16 bits through.
|
|
out pins, 24 side 0 [1]
|
|
// Set WR high and delay to next byte.
|
|
nop side 1 [1]
|
|
// Output the second byte and set TFT_WRITE low.
|
|
out pins, 8 side 0 [1]
|
|
// Set WR high and jump back to start.
|
|
jmp start_tx side 1
|
|
|
|
// Transmit an 8 bit value (LS 8 bits of 32 bits).
|
|
public start_8:
|
|
// Fetch the next 32 bit value from the TX FIFO and set TFT_WR high.
|
|
pull side 1
|
|
// Write the first byte (LSB) and sets WR low. This also
|
|
// shifts the unused top 24 bits through.
|
|
out pins, 32 side 0 [1]
|
|
// Jump to start
|
|
jmp start_tx side 1
|
|
|
|
// Transmit a set window command sequence.
|
|
public set_addr_window:
|
|
// Loop count in x (to send caset, paset and ramwr commands).
|
|
set x, 2 side 1
|
|
pull_cmd:
|
|
// Set TFT_DC low.
|
|
set pins, 0
|
|
// Fetch caset, paset or ramwr.
|
|
pull
|
|
// Output LS byte (caset, paset or ramwr), discarding top 24 bits, set TFT_WR low.
|
|
out pins, 32 side 0
|
|
// Jump to end if 3rd cmd byte ramwr sent (x == 0)
|
|
jmp !x, end_set_addr
|
|
// pull next start and end coordinates, TFT_WR high.
|
|
pull side 1
|
|
// Set TFT_DC high.
|
|
set pins, 1
|
|
send_xy:
|
|
// Output byte, TFT_WR low.
|
|
out pins, 8 side 0 [1]
|
|
// Loop until 4 bytes sent, TFT_WR high.
|
|
jmp !osre, send_xy side 1 [1]
|
|
end_set_addr:
|
|
// Loop back for next command and write last command.
|
|
jmp x--, pull_cmd side 1
|
|
// Set DC high.
|
|
set pins, 1
|
|
// Auto-wrap back to start_tx.
|
|
.wrap |