Hello!
I have a problem with the Atmel128 i2c environment.
I want to read out the k30 co2-sensormodul from senseair.
On this sensor the i2c communication is implemented in software.
Because of that there is an advice in the datasheet
that it might come to problems during the i2c communication
caused by the long response time of the sensor.
The problem was that after an undetermined time the atmel128 i2c
components got in an incorrect state out of which the software can’t
recover.The bus lines stayed high and the return value was EBUSY.
The only way to make the software run fine again was to reset
the node with the watchdog.
However this solution is inadequately.
I analyzed the Atm128I2CMasterPacketP Component and found out that
while the node was in the incorrect state the Atm128I2CMasterPacketP
returned with EBUSY in the else-block at line 220 in the I2CPacket.read()
command.
To solve the problem I added the i2c_abort(EBUSY) call in the else-block. (1,2)
(same for the I2C.write() command, see software snippet below (2,3))
After that it seemed to work fine.
Now the software recovers out of the incorrect state.
Had somebody else this problem or tested the atmel128 i2c components with slow
i2c sensors?
Is it possible that in this else-Block should be a call to the
i2c_abort(EBUSY)-function?
However there seems to be another bad state, which fortunately occurs more
rarely.
In this state the return value is EOFF and the bus lines also are in high
state.
I tried to add the i2c_abort-function in the else if block above,
but this seemed not to solve the problem. (see the software snippet below)
Has anyone an idea how to solve that problem?
Best regards!
Sebastian
Modified Atm128I2CMasterPacketP.nc:
async command error_t I2CPacket.read(i2c_flags_t flags, uint16_t addr, uint8_t
len, uint8_t* data) {
atomic {
if (state == I2C_IDLE) {
state = I2C_BUSY;
}
else if (state == I2C_OFF) {
i2c_abort(EOFF); //added...1
return EOFF;
}
else {
i2c_abort(EBUSY); //added...2
return EBUSY;
}
}
...
async command error_t I2CPacket.write(i2c_flags_t flags, uint16_t addr, uint8_t
len, uint8_t* data) {
atomic {
if (state == I2C_IDLE) {
state = I2C_BUSY;
}
else if (state == I2C_OFF) {
i2c_abort(EOFF); //added...3
return EOFF;
}
else {
i2c_abort(EBUSY); //added...4
return EBUSY;
}
}
--
Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir
belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de
_______________________________________________
Tinyos-help mailing list
[email protected]
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
