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I need more gpio

PostPosted: Mon Jul 20, 2015 12:23 pm
by niqingliang2003
hello, the board has 48 gpios, but I need more, mainly for two camera, for motor.

1. I found only one I2C in PEC_POWER, where is the other one provided by zynq?

2. can I connect the PEC_SOUTH/PEC_NORTH to zynq directly? maybe through modifing configuration of Epiphany?

Re: I need more gpio

PostPosted: Mon Jul 20, 2015 8:11 pm
by tnt
No, south and noth pec are not GPIOs, they're dedicated e-links interface.

However the GPIOs that you have are _really_ fast. Allowing time multiplexing or usage of better protocols.

You mention camera : which ones ? For instance, the rpi camera can be connected to this board using only 6 fast GPIOs.

For the motors, how are you driving them ?

Re: I need more gpio

PostPosted: Tue Jul 21, 2015 7:24 am
by niqingliang2003
tnt wrote:No, south and noth pec are not GPIOs, they're dedicated e-links interface.

However the GPIOs that you have are _really_ fast. Allowing time multiplexing or usage of better protocols.

You mention camera : which ones ? For instance, the rpi camera can be connected to this board using only 6 fast GPIOs.

For the motors, how are you driving them ?


for motor: every motor driver chip need 4 pin, one is for pwm (speed), one is for direction, and two is for microstepping.
for camera: I'm using ov's parallel camera, data need 8/10bit, 1 frame sync, 1 line sync, 1 clock, 1 iic clk, 1 iic data, and so on.

indeed, more other chips, e.g. sensor, switch ...

what is rpi camera? Raspberry Pi camera ?

where is the other i2c?

Re: I need more gpio

PostPosted: Tue Jul 21, 2015 11:05 am
by tnt
Yes, I meant the RPi camera. In addition to the 6 high speed line they have I2C and a couple of slow IO (enable/powerdown and led control, nothing critical). But all those slow lines could be multiplexed / shared.

For the motors, the direction and microstep selection could also be serialized. You could use a few daisy chained 74HC595 to have a high number of output for those slow signals and just keep the PWM speed control as a direct connection. Same things for any 'slow' sensor (things like bumper detector), you could serialize them, or use an I2C GPIO controller.

The other I2C isn't routed to any pin, all the MIO pins are taken. But it's available inside the FPGA itself through EMIO if you want and from there you can route it to any of the 48 GPIOs.

Re: I need more gpio

PostPosted: Tue Jul 21, 2015 11:56 am
by niqingliang2003
tnt wrote:Yes, I meant the RPi camera. In addition to the 6 high speed line they have I2C and a couple of slow IO (enable/powerdown and led control, nothing critical). But all those slow lines could be multiplexed / shared.

For the motors, the direction and microstep selection could also be serialized. You could use a few daisy chained 74HC595 to have a high number of output for those slow signals and just keep the PWM speed control as a direct connection. Same things for any 'slow' sensor (things like bumper detector), you could serialize them, or use an I2C GPIO controller.

The other I2C isn't routed to any pin, all the MIO pins are taken. But it's available inside the FPGA itself through EMIO if you want and from there you can route it to any of the 48 GPIOs.


Very Thanks! I'll consider the serial-parallel solution.

Re: I need more gpio

PostPosted: Wed Sep 16, 2015 8:34 pm
by voyager
Hi
I have the same problem with desktop version! want to connect an adc chip with 14 pairs lvds port but my parallella has only 12 pairs! I need just two pairs more :D and embedded version price is high! how could we manage this problem? Any suggestion would be appreciated!
tnx