I2C bus errors are now recoverable. The bus is properly reset
and an error indication is now provided to the caller whenever
a bus error occurs during processing of the transaction list.
For now, the users of the I2C layer just retry infinitely on
failure. The BMP085 and HMC5843 code should be changed to
report errors to its callers to allow a more sensible retry
strategy.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1625 ebee16cc-31ac-478f-84a7-5cbb03baadba
AUTO transitions in the FSM are now handled immediately
after processing each newly injected event rather than only
at the end of the EV ISR.
This consolidation allows the upcoming addition of event
injection from both the EV and ER ISR contexts.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1624 ebee16cc-31ac-478f-84a7-5cbb03baadba
Occasionally, the I2C driver races with the STM32 I2C peripheral
at the end of a bus cycle. This leaves the bus in an errored
state and the stop condition is not properly asserted on the bus.
The polling for the stopped condition was previously implemented
in ISR context since it was expected to be nearly instananeous.
In the error condition, however, the stop condition will never
happen. The polling for this case is now done by the initiating
task (or mainloop on the AHRS) to prevent the timeout condition
from triggering the watchdog.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1623 ebee16cc-31ac-478f-84a7-5cbb03baadba
Differentiate the _FSM_ faulted from the (soon to
exist _BUS_ faulted state.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1621 ebee16cc-31ac-478f-84a7-5cbb03baadba
The transition from the ADDR state to the read state
was broken for non-final reads. The FSM diagram was
also wrong for this transition.
Since reads are always the last transaction in a sequence
in our current usage, this doesn't actually fix any known
bugs.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1350 ebee16cc-31ac-478f-84a7-5cbb03baadba
Since the i2c bus is bidirectional, there are certain
states (eg. part way through a read) where the slave
device is in control of driving the SDA line.
On a cold start (power on), the slave devices are all
quiescent and will not drive the bus. However, on a warm
start (eg. watchdog or jtag restart), it is possible that as
the CPU boots, the slave device may be holding the SDA line
low. This is a bus busy condition and will prevent the I2C
bus master in the CPU from being able to seize the bus during
init.
The fix for this is to clock the i2c bus sufficiently to ensure
that the the slave device finishes its transaction and releases
the bus.
Once the slave has released the bus, the bus master can properly
initialize and assert a STOP condition on the bus.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1349 ebee16cc-31ac-478f-84a7-5cbb03baadba
The STM32 I2C block has a number of errata associated with it.
These errata are primarily related to timing sensitivities between
the peripheral and the interrupt handler. In particular, the
correct generation of the stop bit relies on the I2C IRQ running
immediately and not being held off for any reason.
NOTE: The I2C interrupts must be the highest priority IRQs in the
system to ensure correct operation.
I2C protocol is now implemented as a formal state machine.
See: stm32_i2c_fsm.{dot,jpg} for FSM description.
I2C init is now expressed by const initializers in pios_board.c
for both OP and AHRS boards.
I2C device drivers (ie. bmp085/hmc5843) now pass in const arrays
of an unlimited number of bus transfers to be done atomically.
The I2C adapter driver now handles all bus-level locking across the
list of transactions. Generation of start/restart/stop conditions
are handled automatically over the list of transactions.
Timeouts have been removed from the API for now. May be added
back later.
This driver has run error free on both the OP and AHRS boards for
up to 48hrs but it still sometimes fails earlier than that on the OP
board. There is another possible set of improvements to the driver
that could employ the DMA engine for transfers of >= 2bytes. This
change would reduce the timing sensitivities between the peripheral
and the driver but unfortunately, both the SPI and I2C interfaces
share the DMA1 engine. That means only one of these two peripherals
can use the DMA engine and right now, SPI between OP and AHRS is
already using it.
Failures are currently fatal and will lock up the CPU. This allows
useful information to be obtained in the failure cases.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@1241 ebee16cc-31ac-478f-84a7-5cbb03baadba
Started work on BMP085 driver. Need more information from Bosch to continue.
git-svn-id: svn://svn.openpilot.org/OpenPilot/trunk@61 ebee16cc-31ac-478f-84a7-5cbb03baadba
