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Major changes to the XPLAINBridge software UART code for performance and reliability. New code reduces the number of missed characters and misread characters.

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Dean Camera 15 years ago
parent 2b0d93c129
commit 229935184b
4 changed files with 61 additions and 55 deletions
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1
LUFA/ManPages/ChangeLog.txt
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@ -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

94
Projects/XPLAINBridge/Lib/SoftUART.c
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@ -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;
}
}
}

2
Projects/XPLAINBridge/Lib/SoftUART.h
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@ -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

19
Projects/XPLAINBridge/XPLAINBridge.c
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@ -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)

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