Added I2C slave echo example in examples folder. Using another maple, write a byte and then read.

Slight tidy up.
Reformatted CREDITS file to be in correct order.
Added a note about buffer overrun

Signed-off-by:- Barry Carter <barry.carter@gmail.com>

1 files changed, 110 insertions, 0 deletions

diff --git a/examples/i2c_slave_example.cpp b/examples/i2c_slave_example.cpp
new file mode 100644
index 0000000..98da58c
--- /dev/null
+++ b/examples/i2c_slave_example.cpp
@@ -0,0 +1,110 @@
+/*
+ * i2c_slave example.cpp
+ *
+ *  Created on: 4 Sep 2012
+ *      Author: Barry Carter <barry.carter@gmail.com>
+ */
+#include <wirish/wirish.h>
+#include <i2c.h>
+
+#define USE_BUFFERED_EXAMPLE 1
+
+i2c_msg msg;
+i2c_msg *pmsg = &msg;
+uint8 buffer[255];
+
+uint8 value_to_print = 'A';
+
+void funcrx(i2c_msg *msg)
+{
+    // Received length will be in msg->length
+    char return_data = msg->data[0];
+    value_to_print = return_data;
+}
+
+#if USE_BUFFERED_EXAMPLE == 1
+/* We ARE using a buffer to transmit the data out.
+ * Make sure you fill the buffer with the data AND you set the length correctly
+ */
+void functx(i2c_msg *msg)
+{
+    // Cheeky. We are using the received byte of the data which is currently in
+    // byte 0 to echo it back to the master device
+    //msg->data[0] = 0x01;    // We are re-using the rx buffer here to echo the request back
+    msg->data[1] = 0x02;
+    msg->data[2] = 0x03;
+    msg->data[3] = 0x04;
+    msg->data[4] = 0x05;
+    msg->length = 5;
+}
+
+#else
+
+/* We are NOT using the buffered data transmission
+ * We will get this callback for each outgoing packet. Make sure to call i2c_write
+ * Strickly speaking, we should be sending a NACk on the last byte we want to send
+ * but for this test example I am going to assume the master will NACK it when it
+ * wants to stop.
+ */
+void functx(i2c_msg *msg)
+{
+    i2c_write(I2C1, msg->data[0]);
+}
+
+#endif
+
+
+void setup() {
+    SerialUSB.begin();
+    SerialUSB.println("I2C Slave example");
+
+    // attach the buffer
+    msg.data = buffer;
+
+    /* Init slave mode. Enables master too
+     * We are going to configure the slave device to
+     *  - enable fast I2C (400khz)
+     *  - dual addresses (can have 2 addresses per module)
+     * general call (accepts data writes to 0x00 on a broadcast basis)
+     *
+     * If the buffered example is enabled, then we also enable the
+     * buffer for rx and tx.
+     * Note you can independently enable/disable RX and TX buffers to
+     * allow a buffered read and direct writes. Useful if you don't know how
+     * much the master will read.
+     */
+#if USE_BUFFERED_EXAMPLE == 1
+    i2c_slave_enable(I2C1, I2C_FAST_MODE | I2C_SLAVE_DUAL_ADDRESS | I2C_SLAVE_GENERAL_CALL | I2C_SLAVE_USE_RX_BUFFER | I2C_SLAVE_USE_TX_BUFFER);
+#else
+    i2c_slave_enable(I2C1, I2C_FAST_MODE | I2C_SLAVE_DUAL_ADDRESS | I2C_SLAVE_GENERAL_CALL);
+#endif
+
+    // attach  receive handler
+    i2c_slave_attach_recv_handler(I2C1, &msg, funcrx);
+    // attach transmit handler
+    i2c_slave_attach_transmit_handler(I2C1, &msg, functx);
+
+    // set addresss 1 to 16
+    i2c_slave_set_own_address(I2C1, 0x10);
+    // set addresss 2 to 32
+    i2c_slave_set_own_address2(I2C1, 0x20);
+}
+
+void loop() {
+    SerialUSB.print("Last byte: ");
+    SerialUSB.println(value_to_print);
+}
+
+// Force init() to be called before anything else.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}