Merge pull request #40 from earlephilhower/i2c0

Fix INPUT_PULLUP/DOWN, I2C 0-len probes, timeout

cores/rp2040/wiring_digital.cpp

@@ -21,6 +21,8 @@
 #include "Arduino.h"
 #include <hardware/gpio.h>
 
+static PinMode _pm[30];
+
 extern "C" void pinMode( pin_size_t ulPin, PinMode ulMode ) {
     switch (ulMode) {
         case INPUT:
@@ -31,11 +33,13 @@ extern "C" void pinMode( pin_size_t ulPin, PinMode ulMode ) {
             gpio_init(ulPin);
             gpio_set_dir(ulPin, false);
             gpio_pull_up(ulPin);
+            gpio_put(ulPin, 0);
             break;
         case INPUT_PULLDOWN:
             gpio_init(ulPin);
             gpio_set_dir(ulPin, false);
             gpio_pull_down(ulPin);
+            gpio_put(ulPin, 1);
             break;
         case OUTPUT:
             gpio_init(ulPin);
@@ -43,16 +47,23 @@ extern "C" void pinMode( pin_size_t ulPin, PinMode ulMode ) {
             break;
         default:
             // Error
-            break;
+            return;
     }
+    _pm[ulPin] = ulMode;
 }
 
 extern "C" void digitalWrite( pin_size_t ulPin, PinStatus ulVal ) {
-    if (!gpio_is_dir_out(ulPin)) {
+    if (_pm[ulPin] == INPUT_PULLDOWN) {
         if (ulVal == LOW) {
-            gpio_pull_down(ulPin);
+            gpio_set_dir(ulPin, false);
         } else {
-            gpio_pull_up(ulPin);
+            gpio_set_dir(ulPin, true);
+        }
+    } else if (_pm[ulPin] == INPUT_PULLUP) {
+        if (ulVal == HIGH) {
+            gpio_set_dir(ulPin, false);
+        } else {
+            gpio_set_dir(ulPin, true);
         }
     } else {
         gpio_put(ulPin, ulVal == LOW ? 0 : 1);

libraries/Wire/Wire.cpp

@@ -180,7 +180,7 @@ size_t TwoWire::requestFrom(uint8_t address, size_t quantity, bool stopBit) {
     }
 
     size_t byteRead = 0;
-    _buffLen = i2c_read_blocking(_i2c, address, _buff, quantity, !stopBit);
+    _buffLen = i2c_read_blocking_until(_i2c, address, _buff, quantity, !stopBit, make_timeout_time_ms(50));
     _buffOff = 0;
     return _buffLen;
 }
@@ -189,6 +189,63 @@ size_t TwoWire::requestFrom(uint8_t address, size_t quantity) {
     return requestFrom(address, quantity, true);
 }
 
+static bool _clockStretch(pin_size_t pin) {
+    auto end = time_us_64() + 100;
+    while ((time_us_64() < end) && (!digitalRead(pin))) { /* noop */ }
+    return digitalRead(pin);
+}
+
+bool _probe(int addr, pin_size_t sda, pin_size_t scl, int freq) {
+    int delay = (1000000 / freq) / 2;
+    bool ack = false;
+
+    pinMode(sda, INPUT_PULLUP);
+    pinMode(scl, INPUT_PULLUP);
+    gpio_set_function(scl, GPIO_FUNC_SIO);
+    gpio_set_function(sda, GPIO_FUNC_SIO);
+
+    digitalWrite(sda, HIGH);
+    sleep_us(delay);
+    digitalWrite(scl, HIGH);
+    if (!_clockStretch(scl)) goto stop;
+    digitalWrite(sda, LOW);
+    sleep_us(delay);
+    digitalWrite(scl, LOW);
+    sleep_us(delay);
+    for (int i=0; i<8; i++) {
+        addr <<= 1;
+        digitalWrite(sda, (addr & (1<<7)) ? HIGH : LOW);
+        sleep_us(delay);
+        digitalWrite(scl, HIGH);
+        sleep_us(delay);
+        if (!_clockStretch(scl)) goto stop;
+        digitalWrite(scl, LOW);
+        sleep_us(5); // Ensure we don't change too close to clock edge
+    }
+
+    digitalWrite(sda, HIGH);
+    sleep_us(delay);
+    digitalWrite(scl, HIGH);
+    if (!_clockStretch(scl)) goto stop;
+
+    ack = digitalRead(sda) == LOW;
+    sleep_us(delay);
+    digitalWrite(scl, LOW);
+
+stop:
+    sleep_us(delay);
+    digitalWrite(sda, LOW);
+    sleep_us(delay);
+    digitalWrite(scl, HIGH);
+    sleep_us(delay);
+    digitalWrite(sda, HIGH);
+    sleep_us(delay);
+    gpio_set_function(scl, GPIO_FUNC_I2C);
+    gpio_set_function(sda, GPIO_FUNC_I2C);
+
+    return ack;
+}
+
 // Errors:
 //  0 : Success
 //  1 : Data too long
@@ -196,14 +253,19 @@ size_t TwoWire::requestFrom(uint8_t address, size_t quantity) {
 //  3 : NACK on transmit of data
 //  4 : Other error
 uint8_t TwoWire::endTransmission(bool stopBit) {
-    if (!_running || !_txBegun || !_buffLen) {
+    if (!_running || !_txBegun) {
         return 4; 
     }
-    auto len = _buffLen;
-    auto ret = i2c_write_blocking(_i2c, _addr, _buff, _buffLen, !stopBit);
-    _buffLen = 0;
     _txBegun = false;
+    if (!_buffLen) {
+        // Special-case 0-len writes which are used for I2C probing
+        return _probe(_addr, _sda, _scl, _clkHz) ? 0 : 2;
+    } else {
+        auto len = _buffLen;
+        auto ret = i2c_write_blocking_until(_i2c, _addr, _buff, _buffLen, !stopBit, make_timeout_time_ms(50));
+        _buffLen = 0;
         return (ret == len) ? 0 : 4;
+    }
 }
 
 uint8_t TwoWire::endTransmission() {

libraries/Wire/Wire.h

@@ -40,11 +40,11 @@ public:
     TwoWire(i2c_inst_t *i2c, pin_size_t sda, pin_size_t scl);
 
     // Start as Master
-    void begin();
+    void begin() override;
     // Start as Slave
-    void begin(uint8_t address);
+    void begin(uint8_t address) override;
     // Shut down the I2C interface
-    void end();
+    void end() override;
 
     // Select IO pins to use.  Call before ::begin()
     bool setSDA(pin_size_t sda);
@@ -52,20 +52,20 @@ public:
 
     void setClock(uint32_t freqHz) override;
 
-    void beginTransmission(uint8_t);
+    void beginTransmission(uint8_t) override;
-    uint8_t endTransmission(bool stopBit);
+    uint8_t endTransmission(bool stopBit) override;
-    uint8_t endTransmission(void);
+    uint8_t endTransmission(void) override;
 
-    size_t requestFrom(uint8_t address, size_t quantity, bool stopBit);
+    size_t requestFrom(uint8_t address, size_t quantity, bool stopBit) override;
-    size_t requestFrom(uint8_t address, size_t quantity);
+    size_t requestFrom(uint8_t address, size_t quantity) override;
 
-    size_t write(uint8_t data);
+    size_t write(uint8_t data) override;
-    size_t write(const uint8_t * data, size_t quantity);
+    size_t write(const uint8_t * data, size_t quantity) override;
 
-    virtual int available(void);
+    virtual int available(void) override;
-    virtual int read(void);
+    virtual int read(void) override;
-    virtual int peek(void);
+    virtual int peek(void) override;
-    virtual void flush(void);
+    virtual void flush(void) override;
     void onReceive(void(*)(int));
     void onRequest(void(*)(void));