More speed and quality improvements to the software USART in the AVRISP project.

[pub/lufa.git] / Projects / AVRISP / Lib / PDITarget.c

diff --git a/Projects/AVRISP/Lib/PDITarget.c b/Projects/AVRISP/Lib/PDITarget.c
index e21942a..afcf8b8 100644 (file)
--- a/Projects/AVRISP/Lib/PDITarget.c
+++ b/Projects/AVRISP/Lib/PDITarget.c
@@ -196,19 +196,18 @@ void PDITarget_SendByte(uint8_t Byte)
                IsSending = true;\r
        }\r
 \r
                IsSending = true;\r
        }\r
 \r

-       bool    EvenParityBit = false;\r
-       uint8_t ParityData    = Byte;\r
+       /* Calculate the new USART frame data here while while we wait for a previous byte (if any) to finish sending */\r
+       uint16_t NewUSARTData = ((1 << 11) | (1 << 10) | (0 << 9) | ((uint16_t)Byte << 1) | (0 << 0));\r

 \r
        /* Compute Even parity - while a bit is still set, chop off lowest bit and toggle parity bit */\r
 \r
        /* Compute Even parity - while a bit is still set, chop off lowest bit and toggle parity bit */\r

+       uint8_t ParityData    = Byte;\r

        while (ParityData)\r
        {\r
        while (ParityData)\r
        {\r

-               EvenParityBit ^= true;\r
-               ParityData    &= (ParityData - 1);\r
+               NewUSARTData ^= (1 << 9);\r
+               ParityData   &= (ParityData - 1);\r

        }\r
 \r
        }\r
 \r

-       /* Calculate the new USART frame data here while while we wait for a previous byte (if any) to finish sending */\r
-       uint16_t NewUSARTData = ((1 << 11) | (1 << 10) | ((uint16_t)EvenParityBit << 9) | ((uint16_t)Byte << 1) | (0 << 0));\r
-\r
+       /* Wait until transmitter is idle before writing new data */\r

        while (SoftUSART_BitCount);\r
 \r
        /* Data shifted out LSB first, START DATA PARITY STOP STOP */\r
        while (SoftUSART_BitCount);\r
 \r
        /* Data shifted out LSB first, START DATA PARITY STOP STOP */\r


@@ -258,7 +257,7 @@ uint8_t PDITarget_ReceiveByte(void)
        SoftUSART_BitCount = BITS_IN_FRAME;\r
        while (SoftUSART_BitCount);\r
        \r
        SoftUSART_BitCount = BITS_IN_FRAME;\r
        while (SoftUSART_BitCount);\r
        \r

-       /* Throw away the start, parity and stop bits to leave only the data */\r
+       /* Throw away the parity and stop bits to leave only the data (start bit is already discarded) */\r

        return (uint8_t)SoftUSART_Data;\r
 #endif\r
 }\r
        return (uint8_t)SoftUSART_Data;\r
 #endif\r
 }\r


@@ -280,7 +279,7 @@ void PDITarget_SendBreak(void)
        }\r
 \r
        /* Need to do nothing for a full frame to send a BREAK */\r
        }\r
 \r
        /* Need to do nothing for a full frame to send a BREAK */\r

-       for (uint8_t i = 0; i <= BITS_IN_FRAME; i++)\r
+       for (uint8_t i = 0; i < BITS_IN_FRAME; i++)\r

        {\r
                /* Wait for a full cycle of the clock */\r
                while (PIND & (1 << 5));\r
        {\r
                /* Wait for a full cycle of the clock */\r
                while (PIND & (1 << 5));\r