Diff: mbed_i2c.c

Revision:

0:972f3778c19c

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed_i2c.c	Thu Dec 10 07:39:48 2015 +0000
@@ -0,0 +1,107 @@
+
+#include <stdio.h>
+#include "i2c_api.h"
+#include "gpio_api.h"
+#include "nrf_delay.h"
+
+static i2c_t mbed_i2c_object = {0,};
+PinName mbed_i2c_sda_pin = NC;
+PinName mbed_i2c_scl_pin = NC;
+
+void mbed_i2c_init(PinName sda, PinName scl)
+{
+    if (mbed_i2c_sda_pin == NC) {
+        mbed_i2c_sda_pin = sda;
+        mbed_i2c_scl_pin = scl;
+    }
+
+    i2c_init(&mbed_i2c_object, sda, scl);
+    i2c_frequency(&mbed_i2c_object, 100000);
+}
+
+int mbed_i2c_write(unsigned char slave_addr,
+                   unsigned char reg_addr,
+                   unsigned char length,
+                   unsigned char const *data)
+{
+    int i;
+    slave_addr = slave_addr << 1;
+    i2c_start(&mbed_i2c_object);
+    i2c_byte_write(&mbed_i2c_object, slave_addr);
+    i2c_byte_write(&mbed_i2c_object, reg_addr);
+    for (i = 0; i < length; i++) {
+        i2c_byte_write(&mbed_i2c_object, data[i]);
+    }
+    i2c_stop(&mbed_i2c_object);
+    return 0;
+}
+
+int mbed_i2c_read(unsigned char slave_addr,
+                  unsigned char reg_addr,
+                  unsigned char length,
+                  unsigned char *data)
+{
+    slave_addr = slave_addr << 1;
+    i2c_write(&mbed_i2c_object, slave_addr, &reg_addr, 1, 0);
+    return (i2c_read(&mbed_i2c_object, slave_addr, data, length, 1) == length) ? 0 : 1;
+}
+
+int mbed_i2c_clear(PinName sda, PinName scl)
+{
+    gpio_t sda_io, scl_io;
+
+    if (mbed_i2c_object.i2c) {
+        mbed_i2c_object.i2c->PSELSCL = 31;
+        mbed_i2c_object.i2c->PSELSDA = 31;
+    }
+
+    gpio_init_in(&sda_io, sda);
+
+    if (!gpio_read(&sda_io)) {
+        printf("sda is always 0, i2c bus is not released\r\n");
+        printf("try to clear i2c bus\r\n");
+        gpio_init_out(&scl_io, scl);
+
+        // Clock max 18 pulses worst case scenario(9 for master to send the rest of command and 9
+        // for slave to respond) to SCL line and wait for SDA come high.
+        for (int i = 0; i < 18; i++) {
+            gpio_write(&scl_io, 0);
+            nrf_delay_us(4);
+            gpio_write(&scl_io, 1);
+            nrf_delay_us(4);
+        }
+
+        if (!gpio_read(&sda_io)) {
+            printf("warning! sda is still 0,, i2c bus is not released\r\n");
+        }
+    }
+
+
+    if (mbed_i2c_object.i2c) {
+        mbed_i2c_init(sda, scl);
+    }
+
+    return 0;
+}
+
+void mbed_i2c_enable(void)
+{
+    mbed_i2c_object.i2c->POWER = 1;
+
+    mbed_i2c_init(mbed_i2c_sda_pin, mbed_i2c_scl_pin);
+}
+
+void mbed_i2c_disable(void)
+{
+    gpio_t sda_io, scl_io;
+
+    mbed_i2c_object.i2c->PSELSCL = 31;
+    mbed_i2c_object.i2c->PSELSDA = 31;
+
+
+    mbed_i2c_object.i2c->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
+    mbed_i2c_object.i2c->POWER = 0;
+
+    gpio_init_in(&sda_io, mbed_i2c_sda_pin);
+    gpio_init_in(&scl_io, mbed_i2c_scl_pin);
+}