71 lines
1.8 KiB
C
71 lines
1.8 KiB
C
/**
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* Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
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*
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* SPDX-License-Identifier: BSD-3-Clause
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*/
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// Sweep through all 7-bit I2C addresses, to see if any slaves are present on
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// the I2C bus. Print out a table that looks like this:
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//
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// I2C Bus Scan
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// 0 1 2 3 4 5 6 7 8 9 A B C D E F
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// 0
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// 1 @
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// 2
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// 3 @
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// 4
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// 5
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// 6
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// 7
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//
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// E.g. if slave addresses 0x12 and 0x34 were acknowledged.
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#include <stdio.h>
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#include "pico/stdlib.h"
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#include "hardware/i2c.h"
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// I2C reserves some addresses for special purposes. We exclude these from the scan.
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// These are any addresses of the form 000 0xxx or 111 1xxx
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bool reserved_addr(uint8_t addr) {
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return (addr & 0x78) == 0 || (addr & 0x78) == 0x78;
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}
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int main() {
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// Enable UART so we can print status output
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stdio_init_all();
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// This example will use I2C0 on GPIO4 (SDA) and GPIO5 (SCL)
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i2c_init(i2c0, 100 * 1000);
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gpio_set_function(4, GPIO_FUNC_I2C);
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gpio_set_function(5, GPIO_FUNC_I2C);
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gpio_pull_up(4);
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gpio_pull_up(5);
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printf("\nI2C Bus Scan\n");
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printf(" 0 1 2 3 4 5 6 7 8 9 A B C D E F\n");
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for (int addr = 0; addr < (1 << 7); ++addr) {
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if (addr % 16 == 0) {
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printf("%02x ", addr);
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}
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// Perform a 1-byte dummy read from the probe address. If a slave
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// acknowledges this address, the function returns the number of bytes
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// transferred. If the address byte is ignored, the function returns
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// -1.
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// Skip over any reserved addresses.
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int ret;
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uint8_t rxdata;
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if (reserved_addr(addr))
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ret = PICO_ERROR_GENERIC;
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else
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ret = i2c_read_blocking(i2c0, addr, &rxdata, 1, false);
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printf(ret < 0 ? "." : "@");
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printf(addr % 16 == 15 ? "\n" : " ");
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}
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printf("Done.\n");
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return 0;
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}
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