pio_encode_mov(pio_pindirs, pio_x) gives wrong value #2754

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opened 2025-12-08 05:35:48 -06:00 by PetteriAimonen · 2 comments

PetteriAimonen commented

2025-12-08 05:35:48 -06:00

(Migrated from github.com)

When calling:

pio_encode_mov(pio_pindirs, pio_x);

it returns 0xA081, while according to datasheet the correct value would be 0xA061

I think this is a left-over bug from RP2040 which doesn't support pindirs as mov destination.

When calling: pio_encode_mov(pio_pindirs, pio_x); it returns `0xA081`, while according to datasheet the correct value would be `0xA061` I think this is a left-over bug from RP2040 which doesn't support `pindirs` as `mov` destination.

lurch commented

2025-12-08 09:44:37 -06:00

(Migrated from github.com)

I did a bit of digging, and it looks like you're right.

I compiled these tables of encoding bit-patterns from the PIO chapters of the RP2040 and RP2350 datasheets:
(with bold highlighting where RP2350 differs from RP2040)

Chip	Instruction	Src or Dest	00	01	10	11
RP2040	`WAIT`	Source	GPIO	PIN	IRQ	Reserved
RP2350	`WAIT`	Source	GPIO	PIN	IRQ	JMPPIN

Chip	Instruction	Src or Dest	000	001	010	011	100	101	110	111
RP2040	`IN`	Source	PINS	X	Y	NULL	Reserved	Reserved	ISR	OSR
RP2040	`OUT`	Destination	PINS	X	Y	NULL	PINDIRS	PC	ISR	EXEC
RP2040	`MOV`	Destination	PINS	X	Y	Reserved	EXEC	PC	ISR	OSR
RP2040	`MOV`	Source	PINS	X	Y	NULL	Reserved	STATUS	ISR	OSR
RP2040	`SET`	Destination	PINS	X	Y	Reserved	PINDIRS	Reserved	Reserved	Reserved
RP2350	`IN`	Source	PINS	X	Y	NULL	Reserved	Reserved	ISR	OSR
RP2350	`OUT`	Destination	PINS	X	Y	NULL	PINDIRS	PC	ISR	EXEC
RP2350	`MOV`	Destination	PINS	X	Y	PINDIRS	EXEC	PC	ISR	OSR
RP2350	`MOV`	Source	PINS	X	Y	NULL	Reserved	STATUS	ISR	OSR
RP2350	`SET`	Destination	PINS	X	Y	Reserved	PINDIRS	Reserved	Reserved	Reserved

pio_encode_mov(enum pio_src_dest dest, enum pio_src_dest src) just does

return _pio_encode_instr_and_src_dest(pio_instr_bits_mov, dest, src & 7u);

pio_src_dest is defined as:

enum pio_src_dest {
    pio_pins = 0u,
    pio_x = 1u,
    pio_y = 2u,
    pio_null = 3u | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_DEST,
    pio_pindirs = 4u | _PIO_INVALID_IN_SRC | _PIO_INVALID_MOV_SRC | _PIO_INVALID_MOV_DEST,
    pio_exec_mov = 4u | _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC,
    pio_status = 5u | _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_DEST,
    pio_pc = 5u | _PIO_INVALID_IN_SRC | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC,
    pio_isr = 6u | _PIO_INVALID_SET_DEST,
    pio_osr = 7u | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST,
    pio_exec_out = 7u | _PIO_INVALID_IN_SRC | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC | _PIO_INVALID_MOV_DEST,
};

which explains why pio_encode_mov(pio_pindirs, pio_x); is encoding pio_pindirs as binary 100 instead of the binary 011 that the MOV instruction in RP2350's PIO expects.

So perhaps pio_src_dest needs to be tweaked to add:

#if PICO_PIO_VERSION > 0
    pio_pindirs_mov = 3u _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC,
#endif

and then your example-code would need to do pio_encode_mov(pio_pindirs_mov, pio_x); instead of pio_encode_mov(pio_pindirs, pio_x);.

I did a bit of digging, and it looks like you're right. I compiled these tables of encoding bit-patterns from the PIO chapters of the [RP2040](https://datasheets.raspberrypi.com/rp2040/rp2040-datasheet.pdf) and [RP2350](https://datasheets.raspberrypi.com/rp2350/rp2350-datasheet.pdf) datasheets: (with **bold** highlighting where RP2350 differs from RP2040) | Chip | Instruction | Src or Dest | 00 | 01 | 10 | 11 | | --- | --- | --- | --- | --- | --- | --- | | RP2040 | `WAIT` | Source | GPIO | PIN | IRQ | Reserved | | RP2350 | `WAIT` | Source | GPIO | PIN | IRQ | **JMPPIN** | | Chip | Instruction | Src or Dest | 000 | 001 | 010 | 011 | 100 | 101 | 110 | 111 | | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | | RP2040 | `IN` | Source | PINS | X | Y | NULL | Reserved | Reserved | ISR | OSR | | RP2040 | `OUT` | Destination | PINS | X | Y | NULL | PINDIRS | PC | ISR | EXEC | | RP2040 | `MOV` | Destination | PINS | X | Y | Reserved | EXEC | PC | ISR | OSR | | RP2040 | `MOV` | Source | PINS | X | Y | NULL | Reserved | STATUS | ISR | OSR | | RP2040 | `SET` | Destination | PINS | X | Y | Reserved | PINDIRS | Reserved | Reserved | Reserved | | RP2350 | `IN` | Source | PINS | X | Y | NULL | Reserved | Reserved | ISR | OSR | | RP2350 | `OUT` | Destination | PINS | X | Y | NULL | PINDIRS | PC | ISR | EXEC | | RP2350 | `MOV` | Destination | PINS | X | Y | **PINDIRS** | EXEC | PC | ISR | OSR | | RP2350 | `MOV` | Source | PINS | X | Y | NULL | Reserved | STATUS | ISR | OSR | | RP2350 | `SET` | Destination | PINS | X | Y | Reserved | PINDIRS | Reserved | Reserved | Reserved | [`pio_encode_mov(enum pio_src_dest dest, enum pio_src_dest src)`](https://github.com/raspberrypi/pico-sdk/blob/develop/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h#L381) just does ```c return _pio_encode_instr_and_src_dest(pio_instr_bits_mov, dest, src & 7u); ``` [`pio_src_dest`](https://github.com/raspberrypi/pico-sdk/blob/develop/src/rp2_common/hardware_pio/include/hardware/pio_instructions.h#L64) is defined as: ```c enum pio_src_dest { pio_pins = 0u, pio_x = 1u, pio_y = 2u, pio_null = 3u | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_DEST, pio_pindirs = 4u | _PIO_INVALID_IN_SRC | _PIO_INVALID_MOV_SRC | _PIO_INVALID_MOV_DEST, pio_exec_mov = 4u | _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC, pio_status = 5u | _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_DEST, pio_pc = 5u | _PIO_INVALID_IN_SRC | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC, pio_isr = 6u | _PIO_INVALID_SET_DEST, pio_osr = 7u | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST, pio_exec_out = 7u | _PIO_INVALID_IN_SRC | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC | _PIO_INVALID_MOV_DEST, }; ``` which explains why `pio_encode_mov(pio_pindirs, pio_x);` is encoding `pio_pindirs` as binary `100` instead of the binary `011` that the `MOV` instruction in RP2350's PIO expects. So perhaps `pio_src_dest` needs to be tweaked to add: ```c #if PICO_PIO_VERSION > 0 pio_pindirs_mov = 3u _PIO_INVALID_IN_SRC | _PIO_INVALID_OUT_DEST | _PIO_INVALID_SET_DEST | _PIO_INVALID_MOV_SRC, #endif ``` and then your example-code would need to do `pio_encode_mov(pio_pindirs_mov, pio_x);` instead of `pio_encode_mov(pio_pindirs, pio_x);`.

👍 1

kilograham commented

2026-06-01 13:56:07 -05:00

(Migrated from github.com)