diff options
Diffstat (limited to 'libraries/Wire/src/Wire.cpp')
| -rw-r--r-- | libraries/Wire/src/Wire.cpp | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/libraries/Wire/src/Wire.cpp b/libraries/Wire/src/Wire.cpp index 58916ce..c407776 100644 --- a/libraries/Wire/src/Wire.cpp +++ b/libraries/Wire/src/Wire.cpp @@ -18,6 +18,7 @@ Modified 2012 by Todd Krein (todd@krein.org) to implement repeated starts Modified 2017 by Chuck Todd (ctodd@cableone.net) to correct Unconfigured Slave Mode reboot + Modified 2020 by Greyson Christoforo (grey@christoforo.net) to implement timeouts */ extern "C" { @@ -86,6 +87,52 @@ void TwoWire::setClock(uint32_t clock) twi_setFrequency(clock); } +/*** + * Sets the TWI timeout. + * + * This limits the maximum time to wait for the TWI hardware. If more time passes, the bus is assumed + * to have locked up (e.g. due to noise-induced glitches or faulty slaves) and the transaction is aborted. + * Optionally, the TWI hardware is also reset, which can be required to allow subsequent transactions to + * succeed in some cases (in particular when noise has made the TWI hardware think there is a second + * master that has claimed the bus). + * + * When a timeout is triggered, a flag is set that can be queried with `getWireTimeoutFlag()` and is cleared + * when `clearWireTimeoutFlag()` or `setWireTimeoutUs()` is called. + * + * Note that this timeout can also trigger while waiting for clock stretching or waiting for a second master + * to complete its transaction. So make sure to adapt the timeout to accomodate for those cases if needed. + * A typical timeout would be 25ms (which is the maximum clock stretching allowed by the SMBus protocol), + * but (much) shorter values will usually also work. + * + * In the future, a timeout will be enabled by default, so if you require the timeout to be disabled, it is + * recommended you disable it by default using `setWireTimeoutUs(0)`, even though that is currently + * the default. + * + * @param timeout a timeout value in microseconds, if zero then timeout checking is disabled + * @param reset_with_timeout if true then TWI interface will be automatically reset on timeout + * if false then TWI interface will not be reset on timeout + + */ +void TwoWire::setWireTimeout(uint32_t timeout, bool reset_with_timeout){ + twi_setTimeoutInMicros(timeout, reset_with_timeout); +} + +/*** + * Returns the TWI timeout flag. + * + * @return true if timeout has occured since the flag was last cleared. + */ +bool TwoWire::getWireTimeoutFlag(void){ + return(twi_manageTimeoutFlag(false)); +} + +/*** + * Clears the TWI timeout flag. + */ +void TwoWire::clearWireTimeoutFlag(void){ + twi_manageTimeoutFlag(true); +} + uint8_t TwoWire::requestFrom(uint8_t address, uint8_t quantity, uint32_t iaddress, uint8_t isize, uint8_t sendStop) { if (isize > 0) { |