79 lines
2.2 KiB
Arduino
79 lines
2.2 KiB
Arduino
/* Scan I2C bus for devices.
|
|
*
|
|
* For I2C write addresses: the scanner sends a start,
|
|
* the write address, looks for an ACK, then sends a stop.
|
|
*
|
|
* For I2C read addresses: the scanner sends a start, the
|
|
* read address, looks for an ACK. If there is an ACK, it
|
|
* reads a byte and NACKs it. Finally it sends a stop.
|
|
*
|
|
* When the I2C chip responds to the read address, it
|
|
* outputs data and will miss a stop condition sent
|
|
* immediately after the read address (bus contention).
|
|
*
|
|
* If the I2C chip misses the stop condition, the
|
|
* address scanner will see ghost addresses until the
|
|
* read ends randomly. By reading a byte after any read
|
|
* address that ACKs, there is a chance to NACK the read
|
|
* and properly end the I2C transaction.
|
|
*/
|
|
#include <DigitalIO.h>
|
|
|
|
// Set pin numbers for your configuration.
|
|
const uint8_t SDA_PIN = A4;
|
|
const uint8_t SCL_PIN = A5;
|
|
|
|
SoftI2cMaster i2c(SCL_PIN, SDA_PIN);
|
|
//FastI2cMaster<SCL_PIN, SDA_PIN> i2c;
|
|
//------------------------------------------------------------------------------
|
|
void setup() {
|
|
|
|
Serial.begin(9600);
|
|
while (!Serial);
|
|
|
|
if (!digitalRead(SDA_PIN) && !digitalRead(SCL_PIN)) {
|
|
Serial.println("External pull-up resistors appear to be missing.");
|
|
Serial.println("Many false responses may be detected.");
|
|
Serial.println("Type any character to continue.");
|
|
|
|
while (!Serial.available());
|
|
Serial.println();
|
|
|
|
}
|
|
uint8_t add = 0;
|
|
bool found = false;
|
|
do {
|
|
bool wr = i2c.transfer(add | I2C_WRITE, 0, 0);
|
|
bool rd = i2c.transfer(add | I2C_READ, 0, 0, I2C_CONTINUE);
|
|
if (rd) {
|
|
uint8_t dummy;
|
|
// Must read byte, send NACK, and issue STOP.
|
|
i2c.transferContinue(&dummy, 1);
|
|
}
|
|
if (rd || wr) {
|
|
found = true;
|
|
Serial.print("Device at address: 0X");
|
|
Serial.print(add, HEX);
|
|
Serial.print(" responds to ");
|
|
if (rd) Serial.print("Read");
|
|
if (rd && wr) Serial.print(" and ");
|
|
if (wr) Serial.print("Write");
|
|
Serial.println('.');
|
|
}
|
|
add += 2;
|
|
}
|
|
while (add);
|
|
|
|
if (!found) {
|
|
Serial.println("No devices found.");
|
|
}
|
|
Serial.println("Done");
|
|
}
|
|
//------------------------------------------------------------------------------
|
|
void loop() {
|
|
// Not used.
|
|
}
|
|
|
|
|
|
|