I2C bus timing on BOE & propgcc

jimmy_boy

Hi All. How is the bus timing achived on I2C bus when using the i2c drivers with propgcc?

SRLM

Hi Jimmy Boy, welcome to the forums.

It looks like PropGCC I2C driver is i2c_driver.c, located in /lib/sys/propeller/i2c_driver.c: https://code.google.com/searchframe#1rh7kcLST58/demos/propboe/libsrc/i2c_driver.c

Or, at least that's one of them. It's all C code, compiled down to a cog image. To answer your specific question: it uses waitcnt.

There is also /lib/sys/propeller/i2c_simple.c, which is not cog based (ie, *MM): https://code.google.com/searchframe#1rh7kcLST58/lib/sys/propeller/i2c_simple.c

i2c_simple.c seems to just run as fast as possible, without any timing. This seems a bit awkward, since some I2C devices might not be able to operate as fast as the Propeller runs that code (not to mention the timing jitters).

jimmy_boy

SRLM- thanks for this pointer. Counld'nt get any of the C code running on my prop BOE i2c bus, so Im going back to spin. Have a great day!