Behavioural Port Specs

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Behavioural Port Specs
#1
Dear Sanworks,
I would like to connect an external digital signal to a behavioural port and in particular to the photo-gate in. I have look and couldn't find any information about it for Bpod R2. Could you please let me know what the voltage levels are, is the signal floating or pulled and what are the timing characteristics of the expected signals? My signal is 3.3V.

Also I couldn't find any schematics/board layouts of R2. Are you planning to release those?
 If i'm not mistaken the digital Input is pin 1 on the rj45 socket counting from the left looking at the side of the bpod. 

Thank you for your help!
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#2
Hi e-potis,

The behavior port pinout on r2 is the same as r0.5 - r1. The input line is floating on the state machine side, and pulled high by a 15k pull-up resistor on our port interface board. In future hardware revisions, we may add a second resistor to the state machine side, to pull the line weakly high.

The CAD files for state machine r2 are here.

I hope this helps

-Josh
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#3
(12-13-2018, 01:22 PM)Josh Wrote: Hi e-potis,

The behavior port pinout on r2 is the same as r0.5 - r1. The input line is floating on the state machine side, and pulled high by a 15k pull-up resistor on our port interface board. In future hardware revisions, we may add a second resistor to the state machine side, to pull the line weakly high.

The CAD files for state machine r2 are here.

I hope this helps

-Josh

Thank you for your reply Josh,
Could you please give me some more information on the signal expected by the bpod. Are you using interrupts? What should the voltage levels and the timing be (minimum pulse length? is high = 1)?

Thanks!
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#4
The state machine samples the line every 100 microseconds. If the line changed levels with respect to the previous sample, a behavior event is generated.  A 'Port1In' event is logic high -> low, and 'Port1Out' is logic low -> high. Since the line is sampled every 100 microseconds and there is a small amount of jitter (1 microsecond or so) on the inter-sample interval, you'll be more than safe if you use a 150 microseocond pulse or longer to trigger the state machine. 

-Josh
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