Hey all, I want to do a frequency measurement of a signal (max ~800 Hz) on the Linux side. And I am wondering, which input is connected to the timer on the im.x 6 to do that. Has anybody of you already done that or something similar? Best, Lukas
There are two input-capture channels on the i.MX6 CPU, GPT_CAPTURE1 and GPT_CAPTURE2 (GPT = General Purpose Timer). Freescale's IMX6DQRM reference shows these as alternate pin-mux options on the SD1_DAT0 and SD1_DAT1 pins, and checking UDOO's schematics, I see these routed to PWM_T3C, PWM_T0B, which map to Arduino header pins 3 and 4, respectively ("PWM3", "PWM4"). As to kernel support, I don't know if a Linux driver already exists for the input capture function -- you might want to dig around in <kernelroot>/arch/arm in the mach-mx6, mach-imx, plat-mxc directories. Or ask about GPT_CAPTURE drivers on the Freescale i.MX6 forums. If one exists, it almost certainly isn't built in by default, so you'd need to recompile to enable this, plus necessary pin-mux changes in board-mx6qd_seco_UDOO.h (or board-mx6sdl_seco_UDOO.h for dual). Doing this from the SAM3X side would probably be a lot easier.
