I'm building an interface board for this speakjet chip, that I've studied and it works good. I need to interface more pins from Arduino besides a basic serial pin. I tried the circuits on my own and I'm afraid to damage the pricey chip, and wait another 2 weeks to get another one, so I'm being cautious and getting confused.
Here is the basic diagram:
Pin B1 should be grounded, B2 & B3 should be high (5v) - for normal operation.
For my interface board I would like to tie the pins to Arduino digital output, to toggle different modes on the chip (such as change the baud for example).
It seems there's some type of strong signal on "B1 - MODE" pin. I had 10k resistor between Arduino and the B1 pin, but it seemed the Arduino signal was not strong enough to toggle the ground out of "DEMO MODE".
I tried connected B1 to ground using 10k 5.6k, 3.3k 1k resistor and the pin is still high and chip is still in demo mode. Seems like the only way for me to get out of demo mode is a hard wire to ground.
I'm just confused, should I just not use any resistor between Arduino and this pin - I thought that was kind of risky without any resistors.