I am using the C5510 and want to use the GPIO pins in an open collector mode. I know that in general, it is possible to set the output data register to a 0 and toggle the output enable (direction) bit to allow the output to drive a 0 or to tristate and let a pullup put a 1 on the signal. But the info in the C5510 data book is not clear if you can do this without driving a 1 momentarily. It indicates that you can only write to the data register when in output mode. So if the data register is a 1, the output will be driving a 1 momentarily until you can write a 0 to the data register. I asked my local FAE about this and he contacted the "factory". Three opinions said I could not use the port the way I want. I still don't belive them, but I don't have a DSK yet to test this on. Anyone know for sure if the GPIO port on the C5510 will work this way, allowing me to write a 0 to the output data register while the direction register is still in input mode?
GPIO on C5510 for open collector
Started by ●February 19, 2006