Merge pull request #844 from ahshah/87_Serial_LINENIR_Usage_Fix

Fix serial corruption on x7 chips
SpenceKonde · Sep 5, 2024 · 7cdaa11 · 7cdaa11
2 parents 2bb785e + 0ae2cad
commit 7cdaa11
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Showing 2 changed files with 4 additions and 3 deletions.
diff --git a/avr/cores/tiny/HardwareSerial.cpp b/avr/cores/tiny/HardwareSerial.cpp
@@ -179,11 +179,12 @@
       *_ucsrb |= _udrie;
     #else
       if(!(LINENIR & _BV(LENTXOK))){
-        //The buffer was previously empty, so enable TX Complete interrupt and load first byte.
-        LINENIR = _BV(LENTXOK) | _BV(LENRXOK);
+        // The buffer was previously empty, so load the first byte, then enable 
+        // the TX Complete interrupt
         unsigned char c = _tx_buffer->buffer[_tx_buffer->tail];
         _tx_buffer->tail = (_tx_buffer->tail + 1) & (SERIAL_BUFFER_SIZE - 1);
         LINDAT = c;
+        LINENIR = _BV(LENTXOK) | _BV(LENRXOK);
       }
     #endif
 

diff --git a/avr/cores/tiny/Serial0.cpp b/avr/cores/tiny/Serial0.cpp
@@ -37,7 +37,7 @@
       if(LINSIR & _BV(LTXOK)) {
         //PINA |= _BV(PINA5); //debug
         if (tx_buffer.head == tx_buffer.tail) {
-        // Buffer empty, so disable interrupts
+        // Buffer empty, so disable the Transmit Performed Interrupt
           LINENIR = LENRXOK; //unset LENTXOK
         } else {
           // There is more data in the output buffer. Send the next byte