Hi.
I am working on a canbus system to read the RPM from a vehicle (OBDII connector).
Seems simple enough but the data sheet on the IC is not very clear. I am reading the RXB0D0 & RXB0D1 registers. I am reading both because RPM is two bytes long
and using formula ((A*256)+B)/4. all I get is a random value that does not change as the engine is revved up. I was questioning my register writes and reads
(all 127 of them). I wrote a small program to write $FF to all registers 0 - 127.
When I read them back quite a few are just some random hex number. For example register $01 displays $EB instead of $FF.
When I isolate the register in question ( $01 ) and only write to it I still get $EB.
No matter what I do i cant read the value I wrote to it.
Any ideas?
Thanks
I am working on a canbus system to read the RPM from a vehicle (OBDII connector).
Seems simple enough but the data sheet on the IC is not very clear. I am reading the RXB0D0 & RXB0D1 registers. I am reading both because RPM is two bytes long
and using formula ((A*256)+B)/4. all I get is a random value that does not change as the engine is revved up. I was questioning my register writes and reads
(all 127 of them). I wrote a small program to write $FF to all registers 0 - 127.
When I read them back quite a few are just some random hex number. For example register $01 displays $EB instead of $FF.
When I isolate the register in question ( $01 ) and only write to it I still get $EB.
No matter what I do i cant read the value I wrote to it.
Any ideas?
Thanks
