Initial Release

pio/i2c/i2c_bus_scan.c

@@ -0,0 +1,42 @@
+#include <stdio.h>
+
+#include "pico/stdlib.h"
+#include "pio_i2c.h"
+
+#define PIN_SDA 2
+#define PIN_SCL 3
+
+bool reserved_addr(uint8_t addr) {
+    return (addr & 0x78) == 0 || (addr & 0x78) == 0x78;
+}
+
+int main() {
+    stdio_init_all();
+
+    PIO pio = pio0;
+    uint sm = 0;
+    uint offset = pio_add_program(pio, &i2c_program);
+    i2c_program_init(pio, sm, offset, PIN_SDA, PIN_SCL);
+ 
+    printf("\nPIO I2C Bus Scan\n");
+    printf("   0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F\n");
+
+    for (int addr = 0; addr < (1 << 7); ++addr) {
+        if (addr % 16 == 0) {
+            printf("%02x ", addr);
+        }
+        // Perform a 0-byte read from the probe address. The read function
+        // returns a negative result NAK'd any time other than the last data
+        // byte. Skip over reserved addresses.
+        int result;
+        if (reserved_addr(addr))
+            result = -1;
+        else
+            result = pio_i2c_read_blocking(pio, sm, addr, NULL, 0);
+
+        printf(result < 0 ? "." : "@");
+        printf(addr % 16 == 15 ? "\n" : "  ");
+    }
+    printf("Done.\n");
+    return 0;
+}