From d85f3aeeeefd6926fe71ec8e066adb74f62dc1cc Mon Sep 17 00:00:00 2001
From: fishsoupisgood <github@madingley.org>
Date: Sat, 13 Jun 2020 21:05:45 +0100
Subject: fish

---
 app/not/i2c_bb.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 164 insertions(+)
 create mode 100644 app/not/i2c_bb.c

(limited to 'app/not/i2c_bb.c')

diff --git a/app/not/i2c_bb.c b/app/not/i2c_bb.c
new file mode 100644
index 0000000..3076605
--- /dev/null
+++ b/app/not/i2c_bb.c
@@ -0,0 +1,164 @@
+#include "project.h"
+
+#define SCL 	GPIO6
+#define SDA	GPIO7
+
+static uint8_t
+set (uint8_t sda, uint8_t scl)
+{
+  uint8_t ret;
+  if (sda)
+    gpio_set (GPIOB, SDA);
+  else
+    gpio_clear (GPIOB, SDA);
+
+  if (scl)
+    gpio_set (GPIOB, SCL);
+  else
+    gpio_clear (GPIOB, SCL);
+
+  delay_us (10);
+  ret = (gpio_get (GPIOB, SDA) & SDA) ? 1 : 0;
+
+  return ret;
+}
+
+
+
+
+uint8_t
+i2cb_send (uint8_t wot)
+{
+  uint8_t i;
+
+  printf ("%02x", wot);
+
+  for (i = 0; i < 8; ++i)
+    {
+      set (wot & 0x80, 0);
+      set (wot & 0x80, 1);
+      set (wot & 0x80, 0);
+      wot <<= 1;
+    }
+  set (1, 0);
+  i = set (1, 1);
+  set (1, 0);
+
+  printf ("%c", i ? '!' : '.');
+  return i;
+}
+
+uint8_t
+i2cb_send_addr (uint8_t addr, uint8_t rnw)
+{
+  return i2cb_send (addr << 1 | rnw);
+}
+
+uint8_t
+i2cb_read (uint8_t ack)
+{
+  uint8_t i, wot = 0;
+
+  for (i = 0; i < 8; ++i)
+    {
+      wot <<= 1;
+      set (1, 0);
+      wot |= set (1, 1);
+      set (1, 0);
+    }
+  set (ack, 0);
+  set (ack, 1);
+  set (ack, 0);
+  return wot;
+}
+
+
+void
+i2cb_start (void)
+{
+  printf ("S");
+  set (1, 1);
+  set (0, 1);
+  set (0, 0);
+}
+
+void
+i2cb_stop (void)
+{
+  printf ("R\n");
+  set (0, 0);
+  set (0, 1);
+  set (1, 1);
+}
+
+
+int
+i2cb_start_transaction (uint8_t a, uint8_t rnw)
+{
+  i2cb_start ();
+  return i2cb_send_addr (a, rnw);
+
+}
+
+
+void
+i2cb_reset (void)
+{
+  i2cb_start ();
+  i2cb_stop ();
+  i2cb_start ();
+  i2cb_stop ();
+}
+
+
+
+void
+i2cb_scan (void)
+{
+  uint8_t r;
+  uint16_t i;
+
+  i2cb_reset ();
+
+  printf ("Probing bus\n");
+  for (i = 0; i < 128; ++i)
+    {
+      i2cb_start ();
+      i2cb_stop ();
+      i2cb_start ();
+      r = i2cb_send ((i << 1) | I2C_WRITE);
+      i2cb_stop ();
+
+      if (!r)
+        printf ("Found device at address 0x%x\n", i);
+    }
+  printf ("Done\n");
+  i2cb_reset ();
+
+}
+
+void
+i2cb_init (void)
+{
+  gpio_set_mode (GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL,
+                 SCL);
+  gpio_set_mode (GPIOB, GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN,
+                 SDA);
+
+  set (1, 1);
+#ifdef DEBUG_I2C
+  printf ("T11 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
+#endif
+  set (0, 1);
+#ifdef DEBUG_I2C
+  printf ("T01 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
+#endif
+  set (1, 0);
+#ifdef DEBUG_I2C
+  printf ("T10 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
+#endif
+  set (1, 1);
+#ifdef DEBUG_I2C
+  printf ("T11 %d:%d\n", !!(SDA_IN_REG & SDA_VAL), !!(SCL_IN_REG & SCL_VAL));
+#endif
+}
-- 
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