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author | Michael Janssen <jamuraa@base0.net> | 2013-08-06 23:33:06 -0500 |
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committer | Michael Janssen <jamuraa@base0.net> | 2013-08-06 23:33:06 -0500 |
commit | 6dd0447c12d1b75611ad8f205890913378635719 (patch) | |
tree | 3e90f957fbf5a1a3500fc9b7a603cc5d0eed6fff /LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c | |
parent | d557744503b3787576ad6d4cebdf37e033809f2b (diff) | |
download | lufa-6dd0447c12d1b75611ad8f205890913378635719.tar.gz lufa-6dd0447c12d1b75611ad8f205890913378635719.tar.bz2 lufa-6dd0447c12d1b75611ad8f205890913378635719.zip |
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
Diffstat (limited to 'LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c')
-rw-r--r-- | LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c b/LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c index 166427943..81fbd0784 100644 --- a/LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c +++ b/LUFA/Drivers/Peripheral/XMEGA/TWI_XMEGA.c @@ -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) { |