Steve Martin / libdrv_SoftI2C

Important changes to repositories hosted on mbed.com

Mbed hosted mercurial repositories are deprecated and are due to be permanently deleted in July 2026.

To keep a copy of this software download the repository Zip archive or clone locally using Mercurial.

It is also possible to export all your personal repositories from the account settings page.

Fork of SoftI2C by Erik -

Files at this revision

API Documentation at this revision

Revision 2:b174177b2bf2, committed 2017-09-13

Comitter:
ninensei
Date:
Wed Sep 13 22:36:30 2017 +0000
Parent:
1:05473196d133
Commit message:
Added clocks stretching support

Changed in this revision

SoftI2C.cpp Show annotated file Show diff for this revision Revisions of this file 
--- a/SoftI2C.cpp	Mon Nov 28 19:55:30 2016 +0000
+++ b/SoftI2C.cpp	Wed Sep 13 22:36:30 2017 +0000
@@ -59,11 +59,11 @@
 
 int SoftI2C::read(int ack) {
     int retval = 0;
-    _scl.output();
     
     // Shift the bits out, msb first
     for (int i = 7; i>=0; i--) {
         //SCL low
+        _scl.output();
         _scl.write(0);
         _sda.input();
         wait_us(delay_us);
@@ -73,11 +73,13 @@
         wait_us(delay_us);
         
         //SCL high again
-        _scl.write(1);
+        _scl.input();
+        while (!_scl.read());
         wait_us(delay_us << 1); //wait two delays
     }
     
     // Last cycle to set the ACK
+    _scl.output();
     _scl.write(0);
     if ( ack ) {
         _sda.output();
@@ -87,19 +89,18 @@
     }
     wait_us(delay_us << 1);
     
-    _scl.write(1);
+    _scl.input();
+    while (!_scl.read());
     wait_us(delay_us << 1);
-
     
     return retval;
 }
 
 int SoftI2C::write(int data) {
-     _scl.output();
-     
     // Shift the bits out, msb first
     for (int i = 7; i>=0; i--) {
         //SCL low
+        _scl.output();
         _scl.write(0);
         wait_us(delay_us);
         
@@ -113,18 +114,21 @@
         wait_us(delay_us);
         
         //SCL high again
-        _scl.write(1);
+        _scl.input();
+        while (!_scl.read());
         wait_us(delay_us << 1); //wait two delays
     }
     
     // Last cycle to get the ACK
+    _scl.output();
     _scl.write(0);
     wait_us(delay_us);
     
     _sda.input();
     wait_us(delay_us);
     
-    _scl.write(1);
+    _scl.input();
+    while (!_scl.read());
     wait_us(delay_us);
     int retval = ~_sda.read(); //Read the ack
     wait_us(delay_us);
@@ -139,7 +143,8 @@
         _scl.output();
         _scl.write(0);
         wait_us(delay_us << 1);
-        _scl.write(1);
+        _scl.input();
+        while (!_scl.read());
         wait_us(delay_us << 1);
     }
     // Pull SDA low
@@ -157,6 +162,7 @@
     _sda.write(0);
     wait_us(delay_us);
     _scl.input();
+    while (!_scl.read());
     wait_us(delay_us);
     _sda.input();
     wait_us(delay_us);