first commit

inc/i2c_bitbang.h

@@ -0,0 +1,157 @@
+#ifndef _I2C_BITBANG_H
+#define _I2C_BITBANG_H
+
+#include <stdint.h>
+#include <stdio.h>
+
+#include "ch32fun.h"
+
+#ifndef I2C_SDA_PIN
+#define I2C_SDA_PIN PA1
+#endif
+
+#ifndef I2C_SCL_PIN
+#define I2C_SCL_PIN PA0
+#endif
+
+// decrease to 1 or 0 for Fast Mode (400kHz)
+#ifndef I2C_DELAY_US
+#define I2C_DELAY_US 3
+#endif
+
+#define I2C_ACK 0
+#define I2C_NACK 1
+
+#define SCL_HIGH() funDigitalWrite(I2C_SCL_PIN, 1)
+#define SCL_LOW() funDigitalWrite(I2C_SCL_PIN, 0)
+#define SDA_HIGH() funDigitalWrite(I2C_SDA_PIN, 1)
+#define SDA_LOW() funDigitalWrite(I2C_SDA_PIN, 0)
+#define SDA_READ() funDigitalRead(I2C_SDA_PIN)
+
+static inline void i2c_delay(void) { Delay_Us(I2C_DELAY_US); }
+
+static inline void i2c_init(void) {
+  funGpioInitAll();
+
+  funPinMode(I2C_SDA_PIN, GPIO_CFGLR_OUT_10Mhz_OD);
+  funPinMode(I2C_SCL_PIN, GPIO_CFGLR_OUT_10Mhz_OD);
+
+  // idle bus state
+  SDA_HIGH();
+  SCL_HIGH();
+}
+
+static inline void i2c_start(void) {
+  SDA_HIGH();
+  SCL_HIGH();
+  i2c_delay();
+
+  SDA_LOW();
+  i2c_delay();
+  SCL_LOW();
+}
+
+static inline void i2c_stop(void) {
+  SDA_LOW();
+  i2c_delay();
+  SCL_HIGH();
+  i2c_delay();
+
+  SDA_HIGH();
+  i2c_delay();
+}
+
+// returns 0 (I2C_ACK) if acknowledged, 1 (I2C_NACK) if not
+static inline uint8_t i2c_write_byte(uint8_t byte) {
+  for (uint8_t i = 0; i < 8; i++) {
+    if (byte & 0x80) {
+      SDA_HIGH();
+    } else {
+      SDA_LOW();
+    }
+
+    byte <<= 1;
+    i2c_delay();
+    SCL_HIGH();
+    i2c_delay();
+    SCL_LOW();
+    i2c_delay();
+  }
+
+  // ACK/NACK processing
+  SDA_HIGH();  // release SDA line for slave
+  i2c_delay();
+  SCL_HIGH();
+  i2c_delay();
+
+  uint8_t ack = SDA_READ();
+
+  SCL_LOW();
+  i2c_delay();
+
+  return ack;
+}
+
+// I2C_ACK (0) to request more data, I2C_NACK (1) to end tx
+static inline uint8_t i2c_read_byte(uint8_t ack_control) {
+  uint8_t byte = 0;
+
+  SDA_HIGH();
+
+  for (uint8_t i = 0; i < 8; i++) {
+    byte <<= 1;
+    i2c_delay();
+    SCL_HIGH();  // slave writes data here
+    i2c_delay();
+
+    if (SDA_READ()) {
+      byte |= 1;
+    }
+
+    SCL_LOW();
+  }
+
+  // send ACK/NACK to slave
+  if (ack_control == I2C_ACK) {
+    SDA_LOW();
+  } else {
+    SDA_HIGH();
+  }
+
+  i2c_delay();
+  SCL_HIGH();
+  i2c_delay();
+  SCL_LOW();
+
+  SDA_HIGH();  // release bus
+  i2c_delay();
+
+  return byte;
+}
+
+static inline void i2c_scan(void) {
+  printf("--- I2C Scan Start ---\n");
+  uint8_t found = 0;
+
+  for (uint8_t addr = 0x08; addr < 0x78; addr++) {
+    i2c_start();
+
+    // try to write to the address
+    uint8_t ack = i2c_write_byte((addr << 1) | 0);
+
+    i2c_stop();
+
+    if (ack == I2C_ACK) {
+      printf("Device found at 0x%02X\n", addr);
+      found++;
+      Delay_Ms(1);
+    }
+  }
+
+  if (found == 0) {
+    printf("No I2C devices found.\n");
+  }
+  printf("--- I2C Scan End ---\n");
+}
+
+#endif  // _I2C_BITBANG_H