View Full Version : Optical Encoders Help!!!!!!!!!!!!!
Blazanax
08-02-2011, 00:18
How many optical encoders are we allowed to use on the robot this year?
Chexposito
08-02-2011, 08:23
Well, it depends, i believe it is limitless. The only snag you may have is the number of C-Rio Cards you have and sidecars you have. Other than that i believe those are the only limits... we have left over digital inputs on our sidecar and on the C-Rio itself... We're using 4 encoders, the linetrackers, an optical sensor, and the compressor... how many do you plan to use?
Blazanax
08-02-2011, 22:03
Do you mean how many encoders are we using or compressors?
Chexposito
08-02-2011, 23:05
how many encoders you want to use
You are actually limited to 12 in hardware. Why? The FPGA can only handle 8 Counters and 4 Encoders. the Encoder library uses Encoders for 4x decoding (meaning you can use up to (4) 4x-decoded encoders) and Counters for 1x or 2x decoding (meaning you can have up to (8) 1x or 2x-decoded encoders). 4+8=12, so 12 encoders max.
This assumes that each encoder is either quadrature or otherwise uses the FPGA Counters (such as a gear tooth sensor).
If you need more than 12, your best bet would probably be to use a co-processor to handle the inputs and either feed them to the cRio via SPI, I2C, Serial, or DACs.
Joe Ross
09-02-2011, 00:59
You are actually limited to 12 in hardware. Why? The FPGA can only handle 8 Counters and 4 Encoders. the Encoder library uses Encoders for 4x decoding (meaning you can use up to (4) 4x-decoded encoders) and Counters for 1x or 2x decoding (meaning you can have up to (8) 1x or 2x-decoded encoders). 4+8=12, so 12 encoders max.
This assumes that each encoder is either quadrature or otherwise uses the FPGA Counters (such as a gear tooth sensor).
If you need more than 12, your best bet would probably be to use a co-processor to handle the inputs and either feed them to the cRio via SPI, I2C, Serial, or DACs.
You're limited to 41 jaguars by cost, but each jaguar can read a single encoder using CAN.
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