So, I have one of the PRU's toggling a GPIO output to create a ~50MHz
clock. On the 'scope I can see the voltage of the signal is ~0.8v not 3.3
when it's running more slowly.
This is toggling pin P8:11 (GPIO1_13) by the way, and I'm not sure if
there's any L/C on-board that is slowing it down. I've set up /lib/firmware/
BB-BONE-PRU-00A0.dts to look like:
/*
* pru dts file BB-BONE-PRU-00A0.dts
*/
/dts-v1/;
/plugin/;
/ {
compatible = "ti,beaglebone", "ti,beaglebone-black";
/* identification */
part-number = "BB-BONE-PRU";
version = "00A0";
exclusive-use =
"P8.13";
fragment@0 {
target = <&am33xx_pinmux>;
__overlay__ {
mygpio: pinmux_mygpio{
pinctrl-single,pins = <
0x34 0x0E
>;
};
};
};
fragment@1 {
target = <&ocp>;
__overlay__ {
test_helper: helper {
compatible = "bone-pinmux-helper";
pinctrl-names = "default";
pinctrl-0 = <&mygpio>;
status = "okay";
};
};
};
fragment@2{
target = <&pruss>;
__overlay__ {
status = "okay";
};
};
};
... where I tried to set the slew-rate to 'fast', disable pull-downs, and
set mode 6 for the pin, thus letting me access the pin as r30:15
Is there anything I can do to increase the voltage of the output signal ?
Am I stuck with it ? Or is it an artifact of the pin I happened to choose ?
Cheers
Simon
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