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qmk_firmware
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Bugfixes with the protocol. 

- Bitmasks need to be equal, not just result in non-zero
 - Only read status once in case it changes under us
 - Logical and not binary and when checking for acks on sending
 - We need to stop the bus when receiving the last byte
 - Force the bus into idle mode when we are Initing
This commit is contained in:
Michael Janssen 2013-08-06 23:33:06 -05:00
parent d557744503
commit 6dd0447c12
2 changed files with 21 additions and 12 deletions
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26
LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c
View File

@ -34,6 +34,10 @@
#define __INCLUDE_FROM_TWI_C
#include "../TWI.h"
static inline bool bitmask_is_set(uint8_t byte, uint8_t mask) {
return (byte & mask) == mask;
}
uint8_t TWI_StartTransmission(TWI_t *twi,
const uint8_t SlaveAddress,
const uint8_t TimeoutMS)
@ -45,22 +49,25 @@ uint8_t TWI_StartTransmission(TWI_t *twi,
TimeoutRemaining = (TimeoutMS * 100);
while (TimeoutRemaining)
{
if (twi->MASTER.STATUS & (TWI_MASTER_WIF_bm | TWI_MASTER_ARBLOST_bm))
uint8_t status = twi->MASTER.STATUS;
if (bitmask_is_set(status, TWI_MASTER_WIF_bm | TWI_MASTER_ARBLOST_bm))
{
// Case 1: Arbitration lost. Try again. (or error)
twi->MASTER.ADDR = SlaveAddress;
}
else if (twi->MASTER.STATUS & (TWI_MASTER_WIF_bm | TWI_MASTER_RXACK_bm))
else if (bitmask_is_set(status, TWI_MASTER_WIF_bm | TWI_MASTER_RXACK_bm))
{
// Case 2: No response from slave.
// We need to release the bus.
TWI_StopTransmission(twi);
return TWI_ERROR_SlaveResponseTimeout;
}
else if (twi->MASTER.STATUS & (TWI_MASTER_WIF_bm))
else if (status & TWI_MASTER_WIF_bm)
{
// Case 3: Slave ACK the Write. Ready!
return TWI_ERROR_NoError;
}
else if (twi->MASTER.STATUS & (TWI_MASTER_RIF_bm))
else if (status & TWI_MASTER_RIF_bm)
{
// Case 4: Slave ACK the Read. Ready! (a byte will be read)
return TWI_ERROR_NoError;
@ -73,7 +80,7 @@ uint8_t TWI_StartTransmission(TWI_t *twi,
if (!(TimeoutRemaining)) {
if (twi->MASTER.STATUS & TWI_MASTER_CLKHOLD_bm) {
// Release the bus if we're holding it.
twi->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
TWI_StopTransmission(twi);
}
}
return TWI_ERROR_BusCaptureTimeout;
@ -84,20 +91,20 @@ bool TWI_SendByte(TWI_t *twi, const uint8_t Byte)
// We assume we're ready to write!
twi->MASTER.DATA = Byte;
while (!(twi->MASTER.STATUS & TWI_MASTER_WIF_bm));
return (twi->MASTER.STATUS & TWI_MASTER_WIF_bm) & !(twi->MASTER.STATUS & TWI_MASTER_RXACK_bm);
return (twi->MASTER.STATUS & TWI_MASTER_WIF_bm) && !(twi->MASTER.STATUS & TWI_MASTER_RXACK_bm);
}
bool TWI_ReceiveByte(TWI_t *twi, uint8_t* const Byte,
const bool LastByte)
{
// If we're here, we should already be reading. Wait if we haven't read yet.
if (twi->MASTER.STATUS & (TWI_MASTER_BUSERR_bm | TWI_MASTER_ARBLOST_bm)) {
if (bitmask_is_set(twi->MASTER.STATUS, TWI_MASTER_BUSERR_bm | TWI_MASTER_ARBLOST_bm)) {
return false;
}
while (!(twi->MASTER.STATUS & TWI_MASTER_RIF_bm));
*Byte = twi->MASTER.DATA;
if (LastByte)
twi->MASTER.CTRLC = TWI_MASTER_ACKACT_bm | TWI_MASTER_CMD_RECVTRANS_gc;
twi->MASTER.CTRLC = TWI_MASTER_ACKACT_bm | TWI_MASTER_CMD_STOP_gc;
else
twi->MASTER.CTRLC = TWI_MASTER_CMD_RECVTRANS_gc;
return true;
@ -137,8 +144,8 @@ uint8_t TWI_ReadPacket(TWI_t *twi,
}
}
TWI_StopTransmission(twi);
}
TWI_StopTransmission(twi);
}
return ErrorCode;
@ -153,7 +160,6 @@ uint8_t TWI_WritePacket(TWI_t *twi,
uint8_t Length)
{
uint8_t ErrorCode;
if ((ErrorCode = TWI_StartTransmission(twi, (SlaveAddress & TWI_DEVICE_ADDRESS_MASK) | TWI_ADDRESS_WRITE,
TimeoutMS)) == TWI_ERROR_NoError)
{

7
LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.h
View File

@ -184,8 +184,11 @@
static inline void TWI_Init(TWI_t *twi, const uint8_t Baud) ATTR_ALWAYS_INLINE ATTR_NON_NULL_PTR_ARG(1);
static inline void TWI_Init(TWI_t *twi, const uint8_t Baud)
{
twi->CTRL = 0x00;
twi->MASTER.BAUD = Baud;
twi->MASTER.CTRLA |= TWI_MASTER_ENABLE_bm;
twi->MASTER.CTRLA = TWI_MASTER_ENABLE_bm;
twi->MASTER.CTRLB = 0;
twi->MASTER.STATUS = TWI_MASTER_BUSSTATE_IDLE_gc;
}
/** Turns off the TWI driver hardware. If this is called, any further TWI operations will require a call to
@ -206,7 +209,7 @@
static inline void TWI_StopTransmission(TWI_t *twi) ATTR_ALWAYS_INLINE ATTR_NON_NULL_PTR_ARG(1);
static inline void TWI_StopTransmission(TWI_t *twi)
{
twi->MASTER.CTRLC = TWI_MASTER_CMD_STOP_gc;
twi->MASTER.CTRLC = TWI_MASTER_ACKACT_bm | TWI_MASTER_CMD_STOP_gc;
}
/* Function Prototypes: */