The decoder function on the TIR1000 chip isn't working for us. When we send a signal (to IR_RXD) we don't get anything out on U_RXD (the output stays constant at 3.3 V), based on oscilloscope testing. We have tried resetting and we have tried three different chips and have gotten the same result on all of them. Here are our connections:
VCC: 3.3 V
GND: to ground on USB/uart adapter
CLK: 1.843 MHz sine wave from a function generator
IR_RXD: +3.3 V pulses, about 1.6 microseconds wide, verified on oscilloscope. (we are getting this from the IR_TXD pin on a separate TIR1000 chip. Ultimately this pin will be connected to a photodiode, but we are testing the boards directly together first to verify that they are working as expected).
We can't figure out why no signal is produced on U_RXD. What are we missing?