a little progress

drivers/arm/twi2c.c

@@ -53,7 +53,7 @@ char initialReplyBody[50] = "Initial reply";        // 'Status' response if read
 uint32_t messageCounter = 0;                /* Counts number of messages received to return as part of response */
 
 uint8_t  rxBody[240];                       /* stores last message master sent us (intentionally a few bytes smaller than txBody) */
-uint8_t  txBody[256];                       /* Return message buffer for computed replies */
+uint8_t  txBody[MATRIX_ROWS/2];                       /* Return message buffer for computed replies */
 
 BaseSequentialStream *chp = NULL;           // Used for serial logging
 
@@ -126,19 +126,12 @@ const char hexString[16] = "0123456789abcdef";
  *  Note: Called in interrupt context, so need to be quick!
  */
 void twi2c_slave_message_process(I2CDriver *i2cp) {
-  uint8_t *txPtr = txBody;
-  uint8_t txLen;
 
-  size_t len = i2cSlaveBytes(i2cp);         // Number of bytes received
+  // size_t len = i2cSlaveBytes(i2cp);         // Number of bytes received
 
-  if (len >= 2 && rxBody[0] == 0x01 && rxBody[1] == 0x00) {
-    matrix_row_t matrix[MATRIX_ROWS / 2];
-    matrix_copy(matrix);
-    memcpy(txPtr, matrix, MATRIX_ROWS / 2);
-    txLen = MATRIX_ROWS / 2;
-  }
+  matrix_copy(txBody);
 
-  echoReply.size = txLen;
+  echoReply.size =  MATRIX_ROWS / 2;
   i2cSlaveReplyI(i2cp, &echoReply);
 }
 

keyboards/_qmk_handwire/matrix.c

@@ -55,7 +55,8 @@ void matrix_init(void) {
     right_hand = palReadPad(GPIOC, 13);
 
     // if USB is active, this is the master
-    master = (USB_DRIVER.state == USB_ACTIVE);
+    // master = usbGetDriverStateI(&USB_DRIVER) == USB_ACTIVE;
+    master = right_hand;
 
     if (master) {
       twi2c_master_init();
@@ -127,15 +128,16 @@ matrix_row_t matrix_scan_common(uint8_t row) {
   return data;
 }
 
-void matrix_scan_master(void) {
+const uint8_t command[2] = { 0x01, 0x00 };
+uint8_t other_matrix[MATRIX_ROWS] = { 0 };
 
-  const uint8_t command[2] = { 0x01, 0x00 };
-  uint8_t other_matrix[MATRIX_ROWS];
+void matrix_scan_master(void) {
 
   msg_t resp;
-  resp = twi2c_master_send(slaveI2Caddress/2, command, other_matrix, TIME_INFINITE);
-  printf("%x\n", resp);
+  resp = twi2c_master_send(slaveI2Caddress/2, command, other_matrix, TIME_IMMEDIATE);
+  // printf("%x\n", resp);
 
+  if (resp == MSG_OK) {
     uint8_t * matrix_pointer;
     if (right_hand) {
       matrix_pointer = matrix;
@@ -144,6 +146,7 @@ void matrix_scan_master(void) {
     }
 
     memcpy(matrix_pointer, other_matrix, MATRIX_ROWS / 2);
+  }
 }
 
 uint8_t matrix_scan(void) {