Hello!
I'm trying to create a board that has a 6x4 key matrix. Since the pico is doing a few other tasks, I thought I could offload the matrix scanning to the PIO. I found an example https://github.com/GitJer/Some_RPI-Pico ... matrix_4x4 online, modified it to my application, but cannot get it to work at all. I tested the hardware with non-PIO code and it worked fine, so I think it's something in my application.
This is the assembly codethe code to initialize it:And the code to read it:It seems to be able to differentiate between the input columns being read, but not the output rows, outputting things like 00001000001000000000000000000000 or 00000100000100000100000100000000, where there is a repeat every 6 numbers, as if the row is stuck on. I've tried autoshift on/off, shifting in manually, and a few other things with no changes. Am I misundering a part of the PIO system? Any help is greatly appreciated.
I'm trying to create a board that has a 6x4 key matrix. Since the pico is doing a few other tasks, I thought I could offload the matrix scanning to the PIO. I found an example https://github.com/GitJer/Some_RPI-Pico ... matrix_4x4 online, modified it to my application, but cannot get it to work at all. I tested the hardware with non-PIO code and it worked fine, so I think it's something in my application.
This is the assembly code
Code:
.program button_matrixstart:.wrap_target set pins 1 [31] ; set 0001 on the 4 output pins (activate first row) and wait for the signal to stabilize in pins 6 ; shift the input pins into the ISR set pins 8 [31] ; set 0010 on the 4 output pins (activate second row) and wait for the signal to stabilize in pins 6 ; shift the input pins into the ISR set pins 4 [31] ; set 0100 on the 4 output pins (activate third row) and wait for the signal to stabilize in pins 6 ; shift the input pins into the ISR set pins 2 [31] ; set 1000 on the 4 output pins (activate fourth row) and wait for the signal to stabilize in pins 6 ; shift the input pins into the ISR.wrapCode:
pio = pio1; sm = pio_claim_unused_sm(pio, true); for (int i = 0; i < 4; i++) { pio_gpio_init(pio, base_output + i); } for (int i = 0; i < 6; i++) { pio_gpio_init(pio, base_input + i); gpio_pull_down(base_input + i); } // load the pio program into the pio memory uint offset = pio_add_program(pio, &button_matrix_program); // make a sm config pio_sm_config c = button_matrix_program_get_default_config(offset); sm_config_set_in_pins(&c, base_input); pio_sm_set_consecutive_pindirs(pio, sm, base_output, 4, true); sm_config_set_set_pins(&c, base_output, 4); //6*4=24, so send it once it's full sm_config_set_in_shift(&c, 1, 1, 24); // init the pio sm with the config pio_sm_init(pio, sm, offset, &c); // enable the sm pio_sm_set_enabled(pio, sm, true);Code:
// read the 4x4 matrix int read(void) { // value is used to read from the fifo uint32_t value = 0; // clear the FIFO, we only want a currently pressed key pio_sm_clear_fifos(pio, sm); // give the sm some time to fill the FIFO if a key is being pressed sleep_ms(1); // check that the FIFO isn't empty if (pio_sm_is_rx_fifo_empty(pio, sm)) { return -1; } // read one data item from the FIFO return pio_sm_get(pio, sm); } Statistics: Posted by miakizz — Sat Mar 30, 2024 4:18 am
