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hx711_multi_reader.pio
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hx711_multi_reader.pio
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; MIT License
;
; Copyright (c) 2023 Daniel Robertson
;
; Permission is hereby granted, free of charge, to any person obtaining a copy
; of this software and associated documentation files (the "Software"), to deal
; in the Software without restriction, including without limitation the rights
; to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
; copies of the Software, and to permit persons to whom the Software is
; furnished to do so, subject to the following conditions:
;
; The above copyright notice and this permission notice shall be included in all
; copies or substantial portions of the Software.
;
; THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
; IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
; FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
; AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
; LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
; OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
; SOFTWARE.
; This program functions similarly to the single HX711 reader program. However,
; it has one important difference. Because the state machine has a limited
; input buffer, it cannot store a full raw HX711 value for each possible chip.
; It must also be able to be able to read the input values of each data pin
; simultaneously and do so 24 times for each bit. The state machine must
; therefore output the pin values for each chip it reads.
;
; The program reads each pin as a bitmask. Each bit is the current state of
; each input pin - whether it is high or low. That bitmask is pushed out of
; the state machine as a 32 bit unsigned integer where the 0th bit (the
; least significant bit) is the state of the HX711's data pin connected to
; the base data pin, the 1th bit is the second HX711, the 2th bit is the
; third HX711, and so on. This occurs 24 times. Once for each bit in a raw,
; two's complement HX711 value.
;
; After the 24 bits have been pushed out of the state machine, effectively
; a 2D array of bits has been created. Each row represents the HX711 bit
; number, and each column represents the all the bits for an individual
; chip. For example:
;
; [ 0, 1, 1, ... 0 ] This is the MSB set of bits for each HX711.
; [ 1, 1, 0, ... 1 ] This is the next set of bits for each HX711.
; ...
; [ 0, 0, 1, ... 0 ] This is the LSB set of bits for each HX711.
;
; =========================================================================
;
; The reader program is free-running. It constantly clocks-in data during a
; period guarded by an IRQ flag. An application consuming data from the
; state machine can start reading in data by waiting until the conversion
; period IRQ flag is set and then reading in each push. After reading in
; bits, the same gain setting procedure is followed as with a single HX711.
;
; NOTE: the RX FIFO may have residual data in it at the beginning of a
; conversion period from the previous conversion period. Application code
; should ensure the RX FIFO is empty.
;
.program hx711_multi_reader
.define PUBLIC HZ 10000000
.define CONVERSION_DONE_IRQ_NUM 0
.define DATA_READY_IRQ_NUM 4
.define LOW 0
.define HIGH 1
.define PLACEHOLDER_IN 1
.define READ_BITS 23
.define DEFAULT_GAIN 0
.define GAIN_BITS 32
.define T3 2
.define T4 2
.side_set 1 opt
set x, DEFAULT_GAIN
pull noblock
out x, GAIN_BITS
.wrap_target
wrap_target:
set y, READ_BITS
in null, 32 ; Completely clear the ISR and RX FIFO.
push noblock
wait HIGH irq DATA_READY_IRQ_NUM ; Wait for the IRQ from the other state machine
; to indicate all HX711s are ready for data
; retrieval.
; At this point it is assumed all HX711 chips are
; synchronised.
irq clear CONVERSION_DONE_IRQ_NUM
bitloop:
set pins, HIGH
PUBLIC bitloop_in_pins_bit_count: ; Set a public label to modify the following `in pins`
; instruction.
in pins, PLACEHOLDER_IN
push noblock ; State machine is free-running, so cannot
; allow it to block with autopush.
jmp y-- bitloop side LOW
irq set CONVERSION_DONE_IRQ_NUM
pull noblock side HIGH
out x, GAIN_BITS
jmp !x wrap_target side LOW
mov y, x
gainloop:
set pins, HIGH [T3 - 1]
jmp y-- gainloop side LOW [T4 - 1]
.wrap
% c-sdk {
// MIT License
//
// Copyright (c) 2023 Daniel Robertson
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
#include <assert.h>
#include <stddef.h>
#include "hardware/clocks.h"
#include "hardware/pio.h"
#include "hardware/pio_instructions.h"
#include "hardware/structs/clocks.h"
#include "hx711_multi.h"
#include "util.h"
void hx711_multi_pio_init(hx711_multi_t* const hxm) {
assert(hxm != NULL);
assert(hxm->_pio != NULL);
assert(hxm->_chips_len > 0);
pio_gpio_init(
hxm->_pio,
hxm->_clock_pin);
util_pio_gpio_contiguous_init(
hxm->_pio,
hxm->_data_pin_base,
hxm->_chips_len);
// make sure conversion done is valid and routable
assert(util_routable_pio_interrupt_num_is_valid(
HX711_MULTI_CONVERSION_DONE_IRQ_NUM));
pio_interrupt_clear(
hxm->_pio,
HX711_MULTI_CONVERSION_DONE_IRQ_NUM);
// make sure data ready is valid and not routable
// although this is not strictly necessary
assert(util_pio_interrupt_num_is_valid(
HX711_MULTI_DATA_READY_IRQ_NUM));
assert(!util_routable_pio_interrupt_num_is_valid(
HX711_MULTI_DATA_READY_IRQ_NUM));
pio_interrupt_clear(
hxm->_pio,
HX711_MULTI_DATA_READY_IRQ_NUM);
}
void hx711_multi_reader_program_init(hx711_multi_t* const hxm) {
assert(hxm != NULL);
assert(hxm->_pio != NULL);
hxm->_pio->instr_mem[hxm->_reader_offset + hx711_multi_reader_offset_bitloop_in_pins_bit_count] =
pio_encode_in(pio_pins, hxm->_chips_len);
pio_sm_config cfg = hx711_multi_reader_program_get_default_config(
hxm->_reader_offset);
const float div = (float)(clock_get_hz(clk_sys)) / (uint)hx711_multi_reader_HZ;
sm_config_set_clkdiv(
&cfg,
div);
//clock pin setup
pio_sm_set_out_pins(
hxm->_pio,
hxm->_reader_sm,
hxm->_clock_pin,
1);
pio_sm_set_set_pins(
hxm->_pio,
hxm->_reader_sm,
hxm->_clock_pin,
1);
pio_sm_set_consecutive_pindirs(
hxm->_pio,
hxm->_reader_sm,
hxm->_clock_pin,
1,
true);
sm_config_set_set_pins(
&cfg,
hxm->_clock_pin,
1);
sm_config_set_out_pins(
&cfg,
hxm->_clock_pin,
1);
sm_config_set_sideset_pins(
&cfg,
hxm->_clock_pin);
//data pins
pio_sm_set_in_pins(
hxm->_pio,
hxm->_reader_sm,
hxm->_data_pin_base);
pio_sm_set_consecutive_pindirs(
hxm->_pio,
hxm->_reader_sm,
hxm->_data_pin_base,
hxm->_chips_len,
false); //false = input
sm_config_set_in_pins(
&cfg,
hxm->_data_pin_base);
sm_config_set_in_shift(
&cfg,
false, //false = shift in left
false, //false = autopush disabled
hxm->_chips_len);
pio_sm_clear_fifos(
hxm->_pio,
hxm->_reader_sm);
hxm->_reader_default_config = cfg;
}
%}