91 lines
2.4 KiB
C
91 lines
2.4 KiB
C
#include <stdio.h>
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#include "pico/stdlib.h"
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#include "pico/multicore.h"
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#include "hardware/i2c.h"
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#include "i2c_fifo.h"
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#include "i2c_slave.h"
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#define I2C0_SDA_PIN 4
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#define I2C0_SCL_PIN 5
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#define I2C_SLAVE_ADDRESS 0x10
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static const uint I2C_SLAVE_SDA_PIN = I2C0_SDA_PIN;
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static const uint I2C_SLAVE_SCL_PIN = I2C0_SCL_PIN;
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// The slave implements a 256 byte memory. To write a series of bytes, the master first
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// writes the memory address, followed by the data. The address is automatically incremented
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// for each byte transferred, looping back to 0 upon reaching the end. Reading is done
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// sequentially from the current memory address.
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static struct
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{
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uint8_t mem[256];
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uint8_t mem_address;
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bool mem_address_written;
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} context;
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// Our handler is called from the I2C ISR, so it must complete quickly. Blocking calls /
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// printing to stdio may interfere with interrupt handling.
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static void i2c_slave_handler(i2c_inst_t *i2c, i2c_slave_event_t event) {
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switch (event) {
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case I2C_SLAVE_RECEIVE: // master has written some data
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if (!context.mem_address_written) {
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// writes always start with the memory address
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context.mem_address = i2c_read_byte(i2c);
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context.mem_address_written = true;
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} else {
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// save into memory
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context.mem[context.mem_address] = i2c_read_byte(i2c);
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context.mem_address++;
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}
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break;
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case I2C_SLAVE_REQUEST: // master is requesting data
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// load from memory
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i2c_write_byte(i2c, context.mem[context.mem_address]);
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context.mem_address++;
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break;
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case I2C_SLAVE_FINISH: // master has signalled Stop / Restart
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context.mem_address_written = false;
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break;
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default:
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break;
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}
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}
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void i2c_set_slave_mode_perso(i2c_inst_t *i2c, uint8_t addr) {
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i2c->hw->enable = 0;
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//while( !(i2c->hw->enable_status & 0x1) );
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i2c->hw->sar = addr;
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i2c->hw->con = 0;
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i2c->hw->enable = 1;
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}
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static void setup_slave() {
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gpio_init(I2C_SLAVE_SDA_PIN);
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gpio_set_function(I2C_SLAVE_SDA_PIN, GPIO_FUNC_I2C);
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gpio_pull_up(I2C_SLAVE_SDA_PIN);
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gpio_init(I2C_SLAVE_SCL_PIN);
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gpio_set_function(I2C_SLAVE_SCL_PIN, GPIO_FUNC_I2C);
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gpio_pull_up(I2C_SLAVE_SCL_PIN);
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i2c_slave_init(i2c0, I2C_SLAVE_ADDRESS, &i2c_slave_handler);
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}
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void main(void)
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{
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stdio_init_all();
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setup_slave();
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while(1){
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}
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}
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