diff --git a/LUFA/ManPages/ChangeLog.txt b/LUFA/ManPages/ChangeLog.txt
index 0a2f43a33b6d6238ee272bd5a4fef6f3e50d854e..8164f3084ba1cc3e8a0936dec4d4744cac47d593 100644
--- a/LUFA/ManPages/ChangeLog.txt
+++ b/LUFA/ManPages/ChangeLog.txt
@@ -27,6 +27,7 @@
* - The USB_Device_IsRemoteWakeupSent() and USB_Device_IsUSBSuspended() macros have been deleted, as they are now obsolete
* - Rewrote the implementation of the SwapEndian_16() and SwapEndian_32() functions so that they compile down in most instances to
* minimal loads and stores rather than complicated shifts
+ * - The software UART in the XPLAINBridge has been largely altered to try to improve upon its performance and reliability
*
* <b>Fixed:</b>
* - Fixed AVRISP project sending a LOAD EXTENDED ADDRESS command to 128KB AVRs after programming or reading from
diff --git a/Projects/XPLAINBridge/Lib/SoftUART.c b/Projects/XPLAINBridge/Lib/SoftUART.c
index 02223af982d3c1954303fcdaec9b6ae1d8ece766..458a505cd2f84f96015ff45fbc0d6f937005e839 100644
--- a/Projects/XPLAINBridge/Lib/SoftUART.c
+++ b/Projects/XPLAINBridge/Lib/SoftUART.c
@@ -45,8 +45,8 @@ static uint8_t TX_BitsRemaining;
/** Temporary data variable to hold the byte being transmitted as it is shifted out */
static uint8_t TX_Data;
-/** Current bit mask of the bit being shifted into the received data byte */
-static uint8_t RX_BitMask;
+/** Total number of bits remaining to be received in the current frame */
+static uint8_t RX_BitsRemaining;
/** Temporary data variable to hold the byte being received as it is shifted in */
static uint8_t RX_Data;
@@ -63,89 +63,83 @@ void SoftUART_Init(void)
EICRA = (1 << ISC01);
EIMSK = (1 << INT0);
- /* Start software UART transmission and reception timers */
+ /* Set reception timer compare period and enable compare ISR */
+ OCR1A = BIT_TIME;
+ TIMSK1 = (1 << OCIE1A);
+
+ /* Set transmission timer compare period, enable compare ISR and start the timer */
+ OCR3A = BIT_TIME;
TIMSK3 = (1 << OCIE3A);
- TCCR3B = (1 << CS30);
- TCCR1B = (1 << CS10);
+ TCCR3B = ((1 << CS30) | (1 << WGM32));
}
/** ISR to detect the start of a bit being sent to the software UART. */
ISR(INT0_vect, ISR_BLOCK)
{
- /* Set reception channel to fire 1.5 bits past the beginning of the start bit */
- OCR1A = TCNT1 + (BIT_TIME + (BIT_TIME / 2));
-
- /* Clear the received data temporary variable, reset the current received bit position mask */
- RX_Data = 0;
- RX_BitMask = (1 << 0);
+ /* Reset and start the reception timer */
+ TCNT1 = 0;
+ TCCR1B = ((1 << CS10) | (1 << WGM12));
- /* Clear reception channel ISR flag and enable the bit reception ISR */
- TIFR1 = (1 << OCF1A);
- TIMSK1 = (1 << OCIE1A);
+ /* Reset the number of reception bits remaining counter */
+ RX_BitsRemaining = 8;
/* Disable start bit detection ISR while the next byte is received */
- EIMSK &= ~(1 << INT0);
+ EIMSK = 0;
}
/** ISR to manage the reception of bits to the software UART. */
ISR(TIMER1_COMPA_vect, ISR_BLOCK)
{
- /* Move the reception ISR compare position one bit ahead */
- OCR1A += BIT_TIME;
+ /* Cache the current RX pin value for later checking */
+ uint8_t SRX_Cached = (SRXPIN & (1 << SRX));
/* Check if reception has finished */
- if (RX_BitMask)
+ if (RX_BitsRemaining)
{
- /* Store next bit into the received data variable */
- if (SRXPIN & (1 << SRX))
- RX_Data |= RX_BitMask;
-
/* Shift the current received bit mask to the next bit position */
- RX_BitMask <<= 1;
+ RX_Data >>= 1;
+ RX_BitsRemaining--;
+
+ /* Store next bit into the received data variable */
+ if (SRX_Cached)
+ RX_Data |= (1 << 7);
}
else
{
- /* Reception complete, store the received byte */
- RingBuffer_Insert(&UARTtoUSB_Buffer, RX_Data);
-
- /* Disable the reception ISR as all data has now been received, re-enable start bit detection ISR */
- TIMSK1 = 0;
+ /* Disable the reception timer as all data has now been received, re-enable start bit detection ISR */
+ TCCR1B = 0;
EIFR = (1 << INTF0);
EIMSK = (1 << INT0);
+
+ /* Reception complete, store the received byte if stop bit valid */
+ if (SRX_Cached)
+ RingBuffer_Insert(&UARTtoUSB_Buffer, RX_Data);
}
}
/** ISR to manage the transmission of bits via the software UART. */
ISR(TIMER3_COMPA_vect, ISR_NOBLOCK)
{
- /* Move the transmission ISR compare position one bit ahead */
- OCR3A += BIT_TIME;
-
/* Check if transmission has finished */
if (TX_BitsRemaining)
{
- /* Check if we are sending a data bit, or the start bit */
- if (--TX_BitsRemaining != 9)
- {
- /* Set the TX line to the value of the next bit in the byte to send */
- if (TX_Data & (1 << 0))
- STXPORT &= ~(1 << STX);
- else
- STXPORT |= (1 << STX);
-
- /* Shift the transmission byte to move the next bit into position */
- TX_Data >>= 1;
- }
+ /* Set the TX line to the value of the next bit in the byte to send */
+ if (TX_Data & (1 << 0))
+ STXPORT &= ~(1 << STX);
else
- {
- /* Start bit - keep TX line low */
- STXPORT &= ~(1 << STX);
- }
+ STXPORT |= (1 << STX);
+
+ /* Shift the transmission byte to move the next bit into position and decrement the bits remaining counter */
+ TX_Data >>= 1;
+ TX_BitsRemaining--;
}
else if (USBtoUART_Buffer.Count)
{
+ /* Start bit - TX line low */
+ STXPORT &= ~(1 << STX);
+
/* Transmission complete, get the next byte to send (if available) */
- TX_Data = ~RingBuffer_Remove(&USBtoUART_Buffer);
- TX_BitsRemaining = 10;
+ TX_Data = ~RingBuffer_Remove(&USBtoUART_Buffer);
+ TX_BitsRemaining = 9;
}
-}
+}
diff --git a/Projects/XPLAINBridge/Lib/SoftUART.h b/Projects/XPLAINBridge/Lib/SoftUART.h
index a685a6d8faf0285e95d2401a07c263b998fa8c57..a107d48a8f8ea18dfd4740444bb5d0c6ec2d798f 100644
--- a/Projects/XPLAINBridge/Lib/SoftUART.h
+++ b/Projects/XPLAINBridge/Lib/SoftUART.h
@@ -43,7 +43,7 @@
/* Macros: */
#define BAUD 9600
- #define BIT_TIME ((F_CPU + (BAUD / 2)) / BAUD)
+ #define BIT_TIME ((F_CPU / BAUD) - 1)
#define SRX PD0
#define SRXPIN PIND
diff --git a/Projects/XPLAINBridge/XPLAINBridge.c b/Projects/XPLAINBridge/XPLAINBridge.c
index 4ba9fd99186f04043b4c5a394123887bd4a6f039..c08dfe980caac07389cc99b5ec23cd790469e268 100644
--- a/Projects/XPLAINBridge/XPLAINBridge.c
+++ b/Projects/XPLAINBridge/XPLAINBridge.c
@@ -76,7 +76,6 @@ RingBuff_t UARTtoUSB_Buffer;
int main(void)
{
SetupHardware();
- V2Protocol_Init();
RingBuffer_InitBuffer(&USBtoUART_Buffer);
RingBuffer_InitBuffer(&UARTtoUSB_Buffer);
@@ -127,9 +126,15 @@ void UARTBridge_Task(void)
if (CDC_Device_BytesReceived(&VirtualSerial_CDC_Interface))
RingBuffer_Insert(&USBtoUART_Buffer, CDC_Device_ReceiveByte(&VirtualSerial_CDC_Interface));
- /* Read bytes from the UART receive buffer into the USB IN endpoint */
- if (UARTtoUSB_Buffer.Count)
- CDC_Device_SendByte(&VirtualSerial_CDC_Interface, RingBuffer_Remove(&UARTtoUSB_Buffer));
+ /* Check if the software UART flush timer has expired */
+ if (TIFR0 & (1 << TOV0))
+ {
+ TIFR0 |= (1 << TOV0);
+
+ /* Read bytes from the UART receive buffer into the USB IN endpoint */
+ while (UARTtoUSB_Buffer.Count)
+ CDC_Device_SendByte(&VirtualSerial_CDC_Interface, RingBuffer_Remove(&UARTtoUSB_Buffer));
+ }
CDC_Device_USBTask(&VirtualSerial_CDC_Interface);
}
@@ -174,6 +179,9 @@ void EVENT_USB_Device_ConfigurationChanged(void)
if (CurrentFirmwareMode == MODE_USART_BRIDGE)
{
EndpointConfigSuccess &= CDC_Device_ConfigureEndpoints(&VirtualSerial_CDC_Interface);
+
+ /* Configure the UART flush timer */
+ TCCR0B = ((1 << CS02) | (1 << CS00));
}
else
{
@@ -186,6 +194,9 @@ void EVENT_USB_Device_ConfigurationChanged(void)
ENDPOINT_DIR_IN, AVRISP_DATA_EPSIZE,
ENDPOINT_BANK_SINGLE);
#endif
+
+ /* Configure the V2 protocol packet handler */
+ V2Protocol_Init();
}
if (EndpointConfigSuccess)