I think its called 8-bit parallel transfer? Maybe?
May 3, 2011
I got a hold of a nifty speech recognition unit after seeing it work here. The kit works quite well and includeds a little display consisting of a couple 7-segment LED's and some drivers. The two drivers are HCF4511BE BCS to seven segment latch/decoder/drivers. They, through a 10 pin header (8 data and power) then talk to a SN74LS373N (on the main board) which the datasheet says is a
OCTAL TRANSPARENT LATCH
WITH 3-STATE OUTPUTS;
OCTAL D-TYPE FLIP-FLOP
WITH 3-STATE OUTPUT
Now it seems that I need ol' Walter to talk to this speech recognition unit via the 8 data pins that normally go to the LED display. I sorta assumed all along that a simple I/O expander would plug right in, no problem. I even etched a little PCB to do just this however, it seems I have run into a problem. It looks like the SN74LS373N is spitting out 8 bits of data, but it is not staying on ("latching" is the word?) I guess the latching is being done by the LED drivers. When I use my I/O expander, I can't seem to "catch" the change of the pins, it happens too quick. I can see this change happen when I run these same 8 output pins into the logic analyzer of my O-scope.
Simple question, how do I get 8 pin parallel data into some kinda chip and out to the robot via i2c? --or-- Is this as simple as using the interrupt pin on the i/o expander and doing a super-quick check of the pins every time we get an interrupt. I am hesitant to go with this interrupt idea --it would require a lot of wiring changes just to get that one pin, not to mention, it would probably cost me a cog just to keep an eye on it. I would much rather use a magical chip that would fix everything.