From 6947560e75b012a703979b5141f82ec2fc73b932 Mon Sep 17 00:00:00 2001
From: Hasan Unlu <hasanunlu9@gmail.com>
Date: Tue, 28 Aug 2018 22:12:26 -0700
Subject: HiFive-1 board bit-bang i2c demo

Bit-bang i2c which is running around 400KHz. MPU6050 is used as an example device.
---
 software/i2c_demo/.gitignore |   1 +
 software/i2c_demo/Makefile   |   6 +
 software/i2c_demo/i2c_demo.c | 318 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 325 insertions(+)
 create mode 100644 software/i2c_demo/.gitignore
 create mode 100644 software/i2c_demo/Makefile
 create mode 100644 software/i2c_demo/i2c_demo.c

(limited to 'software/i2c_demo')

diff --git a/software/i2c_demo/.gitignore b/software/i2c_demo/.gitignore
new file mode 100644
index 0000000..7a8011b
--- /dev/null
+++ b/software/i2c_demo/.gitignore
@@ -0,0 +1 @@
+i2c_demo
diff --git a/software/i2c_demo/Makefile b/software/i2c_demo/Makefile
new file mode 100644
index 0000000..ef29ef2
--- /dev/null
+++ b/software/i2c_demo/Makefile
@@ -0,0 +1,6 @@
+TARGET = i2c_demo
+C_SRCS += i2c_demo.c
+CFLAGS += -O2 -fno-builtin-printf
+
+BSP_BASE = ../../bsp
+include $(BSP_BASE)/env/common.mk
diff --git a/software/i2c_demo/i2c_demo.c b/software/i2c_demo/i2c_demo.c
new file mode 100644
index 0000000..4011c09
--- /dev/null
+++ b/software/i2c_demo/i2c_demo.c
@@ -0,0 +1,318 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "platform.h"
+#include <string.h>
+#include <unistd.h>
+#include <math.h>
+#include "stdatomic.h"
+
+#define MPU6050_ADDR 0x68
+
+#define MPU6050_RA_ACCEL_XOUT_H     0x3B
+#define MPU6050_RA_ACCEL_XOUT_L     0x3C
+#define MPU6050_RA_ACCEL_YOUT_H     0x3D
+#define MPU6050_RA_ACCEL_YOUT_L     0x3E
+#define MPU6050_RA_ACCEL_ZOUT_H     0x3F
+#define MPU6050_RA_ACCEL_ZOUT_L     0x40
+#define MPU6050_RA_TEMP_OUT_H       0x41
+#define MPU6050_RA_TEMP_OUT_L       0x42
+#define MPU6050_RA_GYRO_XOUT_H      0x43
+#define MPU6050_RA_GYRO_XOUT_L      0x44
+#define MPU6050_RA_GYRO_YOUT_H      0x45
+#define MPU6050_RA_GYRO_YOUT_L      0x46
+#define MPU6050_RA_GYRO_ZOUT_H      0x47
+#define MPU6050_RA_GYRO_ZOUT_L      0x48
+#define MPU6050_RA_PWR_MGMT_1       0x6B
+#define MPU6050_RA_WHO_AM_I         0x75
+
+#define SDA PIN_8_OFFSET
+#define SCL PIN_9_OFFSET
+
+#define LONG 25 // Equals ~400KHz
+#define SHORT 5
+
+//busy wait for the specified time
+void wait_ms(uint64_t ms) {
+  static const uint64_t ms_tick = RTC_FREQ/1000;
+  volatile uint64_t * mtime  = (uint64_t*) (CLINT_CTRL_ADDR + CLINT_MTIME);
+  uint64_t then = (ms_tick * ms) + *mtime;
+  while(*mtime<then);
+}
+
+inline void delay_number_of_nop(uint32_t count)
+{
+  for(volatile uint32_t j = 0; j < count; j++)
+  {
+    asm("nop");
+  }
+}
+
+_Bool i2c_busy(void)
+{
+  GPIO_REG(GPIO_INPUT_EN) |= ((0x1 << SCL) | (0x1 << SDA));
+  GPIO_REG(GPIO_OUTPUT_EN)  &= ~((0x1 << SCL) | (0x1 << SDA));
+  return (GPIO_REG(GPIO_INPUT_VAL) & ((0x1 << SCL) | (0x1 << SDA))) != ((0x1 << SCL) | (0x1 << SDA));
+}
+
+void i2c_start(void)
+{
+  GPIO_REG(GPIO_INPUT_EN)  &=  ~((0x1 << SDA) | (0x1 << SCL));
+
+  GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+  GPIO_REG(GPIO_OUTPUT_EN)  |=  (0x1 << SDA);
+  delay_number_of_nop(SHORT);
+  GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SCL);
+  GPIO_REG(GPIO_OUTPUT_EN)  |=  (0x1 << SCL);
+}
+
+void i2c_repeated_start(void)
+{
+  delay_number_of_nop(SHORT);
+  GPIO_REG(GPIO_OUTPUT_VAL) |=  (0x1 << SCL);
+  GPIO_REG(GPIO_OUTPUT_EN)  |=  (0x1 << SCL);
+  delay_number_of_nop(SHORT);
+  i2c_start();
+}
+
+
+void i2c_stop(void)
+{
+  GPIO_REG(GPIO_INPUT_EN) |= (0x1 << SCL);
+  GPIO_REG(GPIO_OUTPUT_EN)  &= ~(0x1 << SCL);
+  delay_number_of_nop(SHORT);
+  GPIO_REG(GPIO_INPUT_EN) |= (0x1 << SDA);
+  GPIO_REG(GPIO_OUTPUT_EN)  &= ~(0x1 << SDA);
+}
+
+void i2c_init(void)
+{
+  //GPIO_REG(GPIO_IOF_EN) &= ((0x1 << SCL) | (0x1 << SDA));
+  GPIO_REG(GPIO_OUTPUT_EN) &= ~((0x1 << SCL) | (0x1 << SDA));
+  GPIO_REG(GPIO_PULLUP_EN) |= ((0x1 << SDA) | (0x1 << SCL));
+  GPIO_REG(GPIO_INPUT_EN)  |=  (0x1 << SDA) | (0x1 << SCL);
+}
+
+void i2c_send_bytes_rs(uint8_t* data, uint8_t size, _Bool rs, uint8_t* data_r, uint8_t size_r)
+{
+  uint8_t address_r = data[0] | 0x01;
+
+  for(uint8_t ii=0; ii<size; ii++)
+  {
+    GPIO_REG(GPIO_INPUT_EN)  &= ~(0x1 << SDA);
+    GPIO_REG(GPIO_OUTPUT_EN) |=  (0x1 << SDA);
+    for(uint8_t i=0; i<9; i++)
+    {
+      delay_number_of_nop(SHORT);
+
+      if(i != 8)
+      {
+        if(data[ii] & 0x80)
+          GPIO_REG(GPIO_OUTPUT_VAL) |=  (0x1 << SDA);
+        else
+          GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+      }
+      else
+      {
+        GPIO_REG(GPIO_INPUT_EN)  |=  (0x1 << SDA);
+        GPIO_REG(GPIO_OUTPUT_EN) &= ~(0x1 << SDA);
+        if((GPIO_REG(GPIO_INPUT_VAL) & (0x1 << SDA)) != 0x0)
+        {
+            printf("NO ACK\n");
+        }
+
+        GPIO_REG(GPIO_INPUT_EN)  &= ~(0x1 << SDA);
+        GPIO_REG(GPIO_OUTPUT_EN) |=  (0x1 << SDA);
+        if(rs == 0)
+        {
+          GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+        }
+        else
+        {
+          GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << SDA);
+        }
+
+      }
+      delay_number_of_nop(LONG-SHORT);
+
+      GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << SCL);
+
+      delay_number_of_nop(LONG);
+
+      GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SCL);
+
+      data[ii] <<= 1;
+    }
+  }
+
+  if(rs == 0)
+    return;
+
+  GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << SCL);
+
+  delay_number_of_nop(SHORT);
+
+  GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+
+  delay_number_of_nop(SHORT);
+
+  GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SCL);
+
+  for(uint8_t i=0; i<9; i++)
+  {
+    delay_number_of_nop(SHORT);
+    if(i != 8)
+    {
+      if(address_r & 0x80)
+        GPIO_REG(GPIO_OUTPUT_VAL) |=  (0x1 << SDA);
+      else
+        GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+    }
+    else
+    {
+      GPIO_REG(GPIO_INPUT_EN)  |=  (0x1 << SDA);
+      GPIO_REG(GPIO_OUTPUT_EN) &= ~(0x1 << SDA);
+      if((GPIO_REG(GPIO_INPUT_VAL) & (0x1 << SDA)) != 0x0)
+      {
+          printf("NO ACK\n");
+      }
+    }
+    delay_number_of_nop(LONG-SHORT);
+
+    GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << SCL);
+
+    delay_number_of_nop(LONG);
+
+    GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SCL);
+
+    address_r <<= 1;
+  }
+
+  // Receive Data
+  for(uint8_t ii=0; ii<size_r; ii++)
+  {
+    for(uint8_t i=0; i<9; i++)
+    {
+      GPIO_REG(GPIO_OUTPUT_VAL) |= (0x1 << SCL);
+
+      if(i!=8)
+        data_r[ii] <<= 1;
+
+      delay_number_of_nop(SHORT);
+
+      if(i!=8)
+      {
+        if((GPIO_REG(GPIO_INPUT_VAL) & (0x1 << SDA)) != 0x0)
+        {
+          data_r[ii] |= 0x1;
+        }
+      }
+      else if(ii == (size_r-1))
+      {
+        GPIO_REG(GPIO_INPUT_EN)  &= ~(0x1 << SDA);
+        GPIO_REG(GPIO_OUTPUT_EN) |=  (0x1 << SDA);
+        GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+      } else {
+
+      }
+
+      delay_number_of_nop(LONG-SHORT);
+
+      GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SCL);
+
+      if((i==7) && (ii != (size_r-1))){
+          GPIO_REG(GPIO_INPUT_EN)  &= ~(0x1 << SDA);
+          GPIO_REG(GPIO_OUTPUT_EN) |=  (0x1 << SDA);
+          GPIO_REG(GPIO_OUTPUT_VAL) &= ~(0x1 << SDA);
+      }
+      delay_number_of_nop(LONG);
+
+    }
+
+    if(ii != (size_r-1)){
+          GPIO_REG(GPIO_INPUT_EN)  |=  (0x1 << SDA);
+          GPIO_REG(GPIO_OUTPUT_EN) &= ~(0x1 << SDA);
+          delay_number_of_nop(SHORT);
+    }
+  }
+}
+
+void write_byte(uint8_t address, uint8_t reg_addr, uint8_t val)
+{
+  uint8_t temp[3];
+  uint8_t data;
+  temp[0]=address<<1;
+  temp[1]=reg_addr;
+  temp[2]=val;
+  while(i2c_busy());
+  i2c_start();
+  i2c_send_bytes_rs(temp, sizeof(temp), 0, &data, 1);
+  i2c_stop();
+}
+
+uint8_t read_byte(uint8_t address, uint8_t reg_addr)
+{
+  uint8_t temp[2];
+  uint8_t data;
+  temp[0]=address<<1;
+  temp[1]=reg_addr;
+  while(i2c_busy());
+  i2c_start();
+  i2c_send_bytes_rs(temp, sizeof(temp), 1, &data, 1);
+  i2c_stop();
+  return data;
+}
+
+void read_bytes(uint8_t address, uint8_t reg_addr, uint8_t* data, uint8_t size)
+{
+  uint8_t temp[2];
+  temp[0]=address<<1;
+  temp[1]=reg_addr;
+  while(i2c_busy());
+  i2c_start();
+  i2c_send_bytes_rs(temp, sizeof(temp), 1, data, size);
+  i2c_stop();
+}
+
+int main(int argc, char **argv)
+{
+  uint8_t data;
+  uint8_t accel[6];
+
+  printf("BIT-BANG I2C DEMO with MPU-6050 IMU\n");
+
+  i2c_init();
+
+  printf("Power Management 1: 0x%02X\n", read_byte(MPU6050_ADDR, MPU6050_RA_PWR_MGMT_1));
+  write_byte(MPU6050_ADDR, MPU6050_RA_PWR_MGMT_1, 0x80);
+
+  wait_ms(10);
+
+  printf("Power Management 1: 0x%02X\n", read_byte(MPU6050_ADDR, MPU6050_RA_PWR_MGMT_1));
+  write_byte(MPU6050_ADDR, MPU6050_RA_PWR_MGMT_1, 0x00);
+
+  printf("CHIP_ID: 0x%02X\n", read_byte(MPU6050_ADDR, MPU6050_RA_WHO_AM_I));
+  printf("DONE\n");
+
+  while(1)
+  {
+    //for(uint8_t i=0; i<6; i++){
+    //  accel[i]=read_byte(MPU6050_ADDR, 0x3B+i);
+    //}
+    read_bytes(MPU6050_ADDR, 0x3B, accel, 6);
+    int16_t x_accel = (accel[0]<<8)+accel[1];
+    int16_t y_accel = (accel[2]<<8)+accel[3];
+    int16_t z_accel = (accel[4]<<8)+accel[5];
+
+    float z_g = z_accel;
+    z_g = z_g/16384.0;
+    int32_t z_g_int = z_g*100;
+    z_g_int = abs(z_g_int);
+    printf("Gravity in Z %d.%d\n", z_g_int/100, z_g_int%100);
+
+    //printf("X: %06d, Y: %06d, Z: %06d\n", x_accel, y_accel, z_accel);
+
+    wait_ms(100);
+  }
+
+  return 0;
+}
-- 
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