Make bidirectional communication work between the keyboard halves. Make the set test LED USB command set the test LED of the left half, too.

left/src/bridge_protocol_handler.c

@@ -0,0 +1,40 @@
+#include "bridge_protocol_handler.h"
+#include "test_led.h"
+#include "main.h"
+#include "i2c_addresses.h"
+#include "i2c.h"
+
+void SetError(uint8_t error);
+void SetGenericError();
+void SetResponseByte(uint8_t response);
+
+void SetError(uint8_t error) {
+    BridgeTxBuffer[0] = error;
+}
+
+void SetGenericError()
+{
+    SetError(PROTOCOL_RESPONSE_GENERIC_ERROR);
+}
+
+// Set a single byte as the response.
+void SetResponseByte(uint8_t response)
+{
+    BridgeTxBuffer[1] = response;
+}
+
+void BridgeProtocolHandler()
+{
+    uint8_t commandId = BridgeRxBuffer[0];
+    switch (commandId) {
+        case BRIDGE_COMMAND_GET_KEY_STATES:
+            BridgeTxSize = KEYBOARD_MATRIX_COLS_NUM*KEYBOARD_MATRIX_ROWS_NUM;
+            memcpy(BridgeTxBuffer, keyMatrix.keyStates, BridgeTxSize);
+            break;
+        case BRIDGE_COMMAND_SET_LED:
+            TEST_LED_OFF();
+            BridgeTxSize = 0;
+            TEST_LED_SET(BridgeRxBuffer[1]);
+            break;
+        }
+}

left/src/bridge_protocol_handler.h

@@ -0,0 +1,29 @@
+#ifndef __BRIDGE_PROTOCOL_HANDLER__
+#define __BRIDGE_PROTOCOL_HANDLER__
+
+// Includes:
+
+    #include "fsl_port.h"
+
+// Macros:
+
+    #define BRIDGE_RX_BUFFER_SIZE 100
+    #define BRIDGE_TX_BUFFER_SIZE 100
+
+    #define PROTOCOL_RESPONSE_SUCCESS       0
+    #define PROTOCOL_RESPONSE_GENERIC_ERROR 1
+
+    #define BRIDGE_COMMAND_GET_KEY_STATES 0
+    #define BRIDGE_COMMAND_SET_LED        1
+
+// Variables:
+
+    uint8_t BridgeRxBuffer[BRIDGE_RX_BUFFER_SIZE];
+    uint8_t BridgeTxBuffer[BRIDGE_TX_BUFFER_SIZE];
+    uint8_t BridgeTxSize;
+
+// Functions:
+
+    extern void BridgeProtocolHandler();
+
+#endif

left/src/main.c

@@ -2,14 +2,13 @@
 #include "init_clock.h"
 #include "fsl_port.h"
 #include "fsl_i2c.h"
+#include "main.h"
 #include "key_matrix.h"
 #include "test_led.h"
 #include "i2c_addresses.h"
 #include "i2c.h"
 #include "init_peripherials.h"
-
-#define KEYBOARD_MATRIX_COLS_NUM 7
-#define KEYBOARD_MATRIX_ROWS_NUM 5
+#include "bridge_protocol_handler.h"
 
 key_matrix_t keyMatrix = {
     .colNum = KEYBOARD_MATRIX_COLS_NUM,
@@ -40,12 +39,18 @@ static void i2c_slave_callback(I2C_Type *base, i2c_slave_transfer_t *xfer, void
     switch (xfer->event)
     {
         case kI2C_SlaveTransmitEvent:
-            xfer->data = keyMatrix.keyStates;
-            xfer->dataSize = KEYBOARD_MATRIX_COLS_NUM*KEYBOARD_MATRIX_ROWS_NUM;
+            BridgeProtocolHandler();
+            xfer->data = BridgeTxBuffer;
+            xfer->dataSize = BridgeTxSize;
             break;
         case kI2C_SlaveReceiveEvent:
+            BridgeProtocolHandler();
+            xfer->data = BridgeRxBuffer;
+            xfer->dataSize = BRIDGE_RX_BUFFER_SIZE;
             break;
         case kI2C_SlaveCompletionEvent:
+            xfer->data = NULL;
+            xfer->dataSize = 0;
             break;
         case kI2C_SlaveTransmitAckEvent:
             break;
@@ -64,6 +69,7 @@ int main(void)
     slaveConfig.addressingMode = kI2C_Address7bit/kI2C_RangeMatch;
     I2C_SlaveInit(I2C_BUS_BASEADDR, &slaveConfig);
     I2C_SlaveTransferCreateHandle(I2C_BUS_BASEADDR, &slaveHandle, i2c_slave_callback, NULL);
+    slaveHandle.eventMask |= kI2C_SlaveCompletionEvent;
     I2C_SlaveTransferNonBlocking(I2C_BUS_BASEADDR, &slaveHandle, kI2C_SlaveCompletionEvent);
 
     KeyMatrix_Init(&keyMatrix);

left/src/main.h

@@ -0,0 +1,17 @@
+#ifndef __MAIN_H__
+#define __MAIN_H__
+
+// Includes:
+
+    #include "key_matrix.h"
+
+// Macros:
+
+    #define KEYBOARD_MATRIX_COLS_NUM 7
+    #define KEYBOARD_MATRIX_ROWS_NUM 5
+
+// Variables:
+
+    extern key_matrix_t keyMatrix;
+
+#endif

left/src/test_led.h

@@ -10,13 +10,14 @@
     #define LOGIC_LED_ON  0U
     #define LOGIC_LED_OFF 1U
 
-    #define TEST_LED_GPIO      GPIOA
-    #define TEST_LED_PORT PORTA
-    #define TEST_LED_CLOCK     kCLOCK_PortA
-    #define TEST_LED_PIN  12
+    #define TEST_LED_GPIO  GPIOA
+    #define TEST_LED_PORT  PORTA
+    #define TEST_LED_CLOCK kCLOCK_PortA
+    #define TEST_LED_PIN   12
 
     #define TEST_LED_ON() GPIO_SetPinsOutput(TEST_LED_GPIO, 1U << TEST_LED_PIN)
     #define TEST_LED_OFF() GPIO_ClearPinsOutput(TEST_LED_GPIO, 1U << TEST_LED_PIN)
+    #define TEST_LED_SET(state) GPIO_WritePinOutput(TEST_LED_GPIO, TEST_LED_PIN, !(state))
     #define TEST_LED_TOGGLE() GPIO_TogglePinsOutput(TEST_LED_GPIO, 1U << TEST_LED_GPIO_PIN)
 
 // Functions: