inital commit

1 files changed, 311 insertions, 0 deletions

diff --git a/app/i2c_bb.c b/app/i2c_bb.c
new file mode 100644
index 0000000..f392b5e
--- /dev/null
+++ b/app/i2c_bb.c
@@ -0,0 +1,311 @@
+#include "project.h"
+#include <stdio.h>
+#include <string.h>
+
+#define SDA_BANK GPIOB
+#define SDA_GPIO GPIO7
+
+#define SCL_BANK GPIOB
+#define SCL_GPIO GPIO6
+
+
+#define I2C_READ    1
+#define I2C_WRITE   0
+
+#define OUR_ADDRESS 0x90
+
+
+typedef enum {
+  ST_LOST = 0,
+  ST_ADDRESS_7,
+  ST_ADDRESS_6,
+  ST_ADDRESS_5,
+  ST_ADDRESS_4,
+  ST_ADDRESS_3,
+  ST_ADDRESS_2,
+  ST_ADDRESS_1,
+  ST_ADDRESS_0,
+  ST_ADDRESS_ACK,
+  ST_OUT_7,
+  ST_OUT_6,
+  ST_OUT_5,
+  ST_OUT_4,
+  ST_OUT_3,
+  ST_OUT_2,
+  ST_OUT_1,
+  ST_OUT_0,
+  ST_PREP_OUT_ACK,
+  ST_OUT_ACK,
+  /*Doesn't fall through*/
+  ST_PREP_REG_7,
+  ST_REG_7,
+  ST_REG_6,
+  ST_REG_5,
+  ST_REG_4,
+  ST_REG_3,
+  ST_REG_2,
+  ST_REG_1,
+  ST_REG_0,
+  ST_REG_ACK,
+  ST_PREP_IN_7,
+  ST_IN_7,
+  ST_IN_6,
+  ST_IN_5,
+  ST_IN_4,
+  ST_IN_3,
+  ST_IN_2,
+  ST_IN_1,
+  ST_IN_0,
+  ST_IN_ACK,
+  ST_REG_WRITE,
+  /*Doesn't fall through*/
+
+
+} i2c_state_t;
+
+
+static int dsda;
+
+static void i2c_bb_sda (int sda)
+{
+  dsda = sda;
+
+  if (sda) {
+    gpio_set_mode (SDA_BANK, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, SDA_GPIO);
+    gpio_set (SDA_BANK, SDA_GPIO);
+  } else {
+    gpio_set_mode (SDA_BANK, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, SDA_GPIO);
+    gpio_clear (SDA_BANK, SDA_GPIO);
+  }
+}
+
+
+static void i2c_bb_scl (int scl)
+{
+  if (scl) {
+    gpio_set_mode (SCL_BANK, GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, SCL_GPIO);
+    gpio_set (SCL_BANK, SCL_GPIO);
+  } else {
+    gpio_set_mode (SCL_BANK, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, SCL_GPIO);
+    gpio_clear (SCL_BANK, SCL_GPIO);
+  }
+}
+
+static i2c_state_t state = ST_LOST;
+
+static void i2c_bb_sm (int od, int d, int oc, int c)
+{
+  static int rnw ;
+  static uint8_t sr;
+  static uint8_t reg;
+
+  //Check for START
+  if (oc && c && od && !d) {
+    state = ST_ADDRESS_7;
+    sr = 0;
+  }
+
+  // Check for STOP
+  if (oc && c && !od && d) {
+    state = ST_LOST;
+  }
+
+  switch (state) {
+  case ST_LOST:
+    i2c_bb_sda (1);
+    i2c_bb_scl (1);
+    break;
+  case ST_ADDRESS_7...ST_ADDRESS_0:
+
+    if (! (!oc && c)) {
+      break;
+    }
+
+    //rising scl of a7...a0
+    sr = (sr << 1) | !!d;
+
+    if (state == ST_ADDRESS_0) {
+      if ( (sr & ~I2C_READ) == OUR_ADDRESS) {
+        state++;
+        rnw = d;
+      } else {
+        state = ST_LOST;
+      }
+    } else {
+      state++;
+    }
+
+    break;
+  case ST_ADDRESS_ACK:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of a0
+    i2c_bb_sda (0);
+
+    if (rnw) {
+      state++;
+    } else {
+      state = ST_PREP_REG_7;
+    }
+
+    break;
+  case ST_OUT_7:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of ack
+    i2c_bb_sda (1);
+    //stretch SCL
+    i2c_bb_scl (0);
+    sr = vuart_read (reg);
+    i2c_bb_sda (sr & 0x80);
+    sr <<= 1;
+    i2c_bb_scl (1);
+    state++;
+    break;
+  case ST_OUT_6...ST_OUT_0:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of d6...d0
+    i2c_bb_sda (sr & 0x80);
+    sr <<= 1;
+    state++;
+    break;
+  case ST_PREP_OUT_ACK:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of d0
+    i2c_bb_sda (1);
+    state++;
+    break;
+  case ST_OUT_ACK:
+
+    if (! (!oc && c)) {
+      break;
+    }
+
+    //rising scl of ack
+
+    if (d) {
+      /*They're done with us */
+      state = ST_LOST;
+    } else {
+      /*They want more */
+      state = ST_OUT_7;
+      reg++;
+    }
+
+    break;
+  case ST_PREP_REG_7:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of ack
+    i2c_bb_sda (1);
+    sr = 0;
+    state++;
+    break;
+  case ST_REG_7...ST_REG_0:
+
+    if (! (!oc && c)) {
+      break;
+    }
+
+    //rising scl of r7..r0
+    sr = (sr << 1) | !!d;
+    state++;
+    break;
+  case ST_REG_ACK:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of r0
+    reg = sr;
+    i2c_bb_sda (0);
+    state = ST_PREP_IN_7;
+    break;
+  case ST_PREP_IN_7:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of ack
+    i2c_bb_sda (1);
+    sr = 0;
+    state++;
+    break;
+  case ST_IN_7...ST_IN_0:
+
+    if (! (!oc && c)) {
+      break;
+    }
+
+    //rising scl of i7..i0
+    sr = (sr << 1) | !!d;
+    state++;
+    break;
+  case ST_IN_ACK:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of i0
+    i2c_bb_sda (0);
+    state++;
+    break;
+  case ST_REG_WRITE:
+
+    if (! (oc && !c)) {
+      break;
+    }
+
+    //falling scl of ack
+    i2c_bb_sda (1);
+    //stretch SCL
+    i2c_bb_scl (0);
+    vuart_write (reg, sr);
+    i2c_bb_scl (1);
+    reg++;
+    sr = 0;
+    state = ST_IN_7;
+    break;
+  default:
+    state = ST_LOST;
+  }
+}
+
+
+
+void i2c_bb_init (void)
+{
+  i2c_bb_scl (1);
+  i2c_bb_sda (1);
+}
+
+
+void i2c_bb_poll (void)
+{
+  int sda = gpio_get (SDA_BANK, SDA_GPIO);
+  int scl = gpio_get (SCL_BANK, SCL_GPIO);
+  static int old_sda = 1, old_scl = 1;
+  i2c_bb_sm (old_sda, sda, old_scl, scl);
+  old_scl = scl;
+  old_sda = sda;
+}