pru - output pin

[fogl]

Hello everybody,

I am still trying to run the stepper motor with Machinekit. I configured the hal and i was expecting some step/dir signal on the output pins, but nothing happens (i am monitoring with the oscilloscope).

I tried to generate steps by changing the hpg.stepgen.00.position-cmd signal. I could see the hpg.stepgen.00.position-fb signal that was folowing. So everything seems fine here.

The problem seems to be in the output pin configuration. I tried different kind of options:

- to change the pru number from pru=0 to pru=1

- i tried to change the pin location

Can you please suggest what could be the problem,

Regards

Klemen

my .hal configuration

loadrt threads name1=base-thread period1=100000 fp1=0 name2=servo-thread period2=1000000 fp2=1

loadrt hal_bb_gpio user_leds=0,1,2,3
loadrt hal_pru_generic prucode=/usr/lib/linuxcnc/rt-preempt/pru_generic.bin pru=1 num_stepgens=1 halname=hpg
loadrt siggen num_chan=1

addf bb_gpio.write              base-thread
addf bb_gpio.read               base-thread

addf siggen.0.update            servo-thread
addf hpg.capture-position       servo-thread
addf hpg.update                 servo-thread
ddf bb_gpio.write              base-thread
addf bb_gpio.read               base-thread

addf siggen.0.update            servo-thread
addf hpg.capture-position       servo-thread
addf hpg.update                 servo-thread

setp siggen.0.frequency 2
net ledlight siggen.0.clock => bb_gpio.userled3

# stepper timing parameters in nanoseconds
setp hpg.stepgen.00.dirsetup        200
setp hpg.stepgen.00.dirhold         200
setp hpg.stepgen.00.steplen         1000
setp hpg.stepgen.00.stepspace       1000

setp hpg.stepgen.00.position-scale  20
setp hpg.stepgen.00.maxvel          200.0
setp hpg.stepgen.00.maxaccel        2000.0

#setp hpg.stepgen.00.step_type       0
# P8.12 GPIO1_12 0x4C
# P8.11 GPIO1_13 0x4D
# P8.43 PRU1.out2:  812
# P8.44 PRU1.out4:  813
setp hpg.stepgen.00.steppin          813
setp hpg.stepgen.00.dirpin           812

halcmd: show pin hpg.
Component Pins:
  Comp   Inst Type  Dir         Value  Name                                            Epsilon Flags  linked to:
   106        s32   OUT          7000  hpg.capture-position.time               ----
   106        s32   I/O         13083  hpg.capture-position.tmax               ----
   106        bit   OUT         FALSE  hpg.capture-position.tmax-inc           ----
   106        bit   IN          FALSE  hpg.stepgen.00.control-type             --l-
   106        s32   OUT         45653  hpg.stepgen.00.counts                   --l-
   106        float OUT     -7707.206  hpg.stepgen.00.dbg_err_at_match         0.000010 --l-
   106        float OUT             0  hpg.stepgen.00.dbg_ff_vel               0.000010 --l-
   106        float OUT     -7717.106  hpg.stepgen.00.dbg_pos_minus_prev_cmd   0.000010 --l-
   106        float OUT           0.1  hpg.stepgen.00.dbg_s_to_match           0.000010 --l-
   106        s32   OUT       5368709  hpg.stepgen.00.dbg_step_rate             --l-
   106        float OUT           200  hpg.stepgen.00.dbg_vel_error             0.000010 --l-
   106        u32   IN     0x000000C8  hpg.stepgen.00.dirhold                   --l-
   106        u32   IN     0x0000032C  hpg.stepgen.00.dirpin                   --l-
   106        u32   IN     0x000000C8  hpg.stepgen.00.dirsetup                 --l-
   106        bit   IN           TRUE  hpg.stepgen.00.enable                   --l-
   106        float IN           2000  hpg.stepgen.00.maxaccel                 0.000010 --l-
   106        float IN            200  hpg.stepgen.00.maxvel                   0.000010 --l-
   106        float IN              0  hpg.stepgen.00.minvel                   0.000010 --l-
   106        float IN          10000  hpg.stepgen.00.position-cmd             0.000010 --l-
   106        float OUT      2284.294  hpg.stepgen.00.position-fb               0.000010 --l-
   106        float IN             20  hpg.stepgen.00.position-scale           0.000010 --l-
   106        bit   IN          FALSE  hpg.stepgen.00.stepinvert               --l-
   106        u32   IN     0x000003E8  hpg.stepgen.00.steplen                   --l-
   106        u32   IN     0x0000032D  hpg.stepgen.00.steppin                   --l-
   106        u32   IN     0x000003E8  hpg.stepgen.00.stepspace                 --l-
   106        s32   OUT     385815358  hpg.stepgen.00.test1                     --l-
   106        s32   OUT         45697  hpg.stepgen.00.test2                     --l-
   106        s32   OUT    -1299849246  hpg.stepgen.00.test3                     --l-
   106        float IN              0  hpg.stepgen.00.velocity-cmd             0.000010 --l-
   106        float OUT           200  hpg.stepgen.00.velocity-fb               0.000010 --l-

   106        s32   OUT          8582  hpg.update.time                         ----
   106        s32   I/O         54414  hpg.update.tmax                         ----
   106        bit   OUT         FALSE  hpg.update.tmax-inc                     ----

$ uname -a
Linux beaglebone 4.19.120-bone-rt-r50 #1stretch PREEMPT RT Fri May 8 22:45:31 UTC 2020 armv7l GNU/Linux

$ ls /proc/device-tree/chosen/overlays/
AM335X-PRU-UIO-00A0  BB-ADC-00A0  BB-BONE-eMMC1-01-00A0  BB-HDMI-TDA998x-00A0  name

[Charles Steinkuehler]

You likely need to configure the pin multiplexing for the pins you wish
to use so they can be controlled by the PRU. This is typically done via
a device-tree overlay, or something like cape-universal and the
config-pin utility if you don't like making device-tree files:

https://github.com/cdsteinkuehler/beaglebone-universal-io

On 5/15/2023 1:18 PM, fogl wrote:
>
> Hello everybody,
>
> I am still trying to run the stepper motor with Machinekit. I configured
> the hal and i was expecting some step/dir signal on the output pins, but
> nothing happens (i am monitoring with the oscilloscope).
>
> I tried to generate steps by changing the hpg.stepgen.00.position-cmd
> signal. I could see the hpg.stepgen.00.position-fb signal that was
> folowing. So everything seems fine here.
>
> The problem seems to be in the output pin configuration. I tried different
> kind of options:
> - to change the pru number from pru=0 to pru=1
> - i tried to change the pin location
>
> Can you please suggest what could be the problem,
> Regards
> Klemen
>

> *my .hal configuration*

> *halcmd: show pin hpg.*

> *$ uname -a*

> Linux beaglebone 4.19.120-bone-rt-r50 #1stretch PREEMPT RT Fri May 8
> 22:45:31 UTC 2020 armv7l GNU/Linux
>

> *$ ls /proc/device-tree/chosen/overlays/*

> AM335X-PRU-UIO-00A0 BB-ADC-00A0 BB-BONE-eMMC1-01-00A0
> BB-HDMI-TDA998x-00A0 name
>

--
Charles Steinkuehler
cha...@steinkuehler.net

[fogl]

Thank you for your reply.

Now i generated the device tree overlay to configured the P8_43 to Mode6 (pr1_pru1_pru_r31_2) and P8_44 to Mode6 (pr1_pru1_pru_r31_3). This was successful:

$cat /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/pins | grep 8a8
pin 42 (PIN42) 44e108a8 00000016 pinctrl-single

$cat /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/pins | grep 8ac
pin 43 (PIN43) 44e108ac 00000016 pinctrl-single

i changed my .hal file to use pru1 and set the pins according to  numbering scheme:

loadrt hal_pru_generic prucode=/usr/lib/linuxcnc/rt-preempt/pru_generic.bin pru=1 num_stepgens=1 halname=hpg

setp hpg.stepgen.00.steppin          1843
setp hpg.stepgen.00.dirpin           1844

...but i still see no output on the pins.

I noticed there is also Mode5 PinMux option with the pr_pru_pru_r30 available. Should i use this mode?

Regards

Klemen

[Charles Steinkuehler]

The mode pr1_pru1_pru_r31_* is for PRU input (R31 is the direct input
register). Use the pr_pru_pru_r30 option (R30 is the PRU direct output
register) or something like the config-pin utility and universal overlay
which makes this simple for you, eg:

config-pin P8.43 pruout

--
Charles Steinkuehler
cha...@steinkuehler.net

[fogl]

Thank you for your reply. I modified the device PinMux to Mode5:

$cat /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/pins | grep 8a8
pin 42 (PIN42) 44e108a8 0000000d pinctrl-single

$cat /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/pins | grep 8ac
pin 43 (PIN43) 44e108ac 0000000d pinctrl-single

Now everything works fine, hank you :)

BTW, i did try to $ sudo config-pin P8.43 pruout, but it returned:

P8_43 pinmux file not found!
bash: /sys/devices/platform/ocp/ocp*P8_43_pinmux/state: No such file or directory

Cannot write pinmux file: /sys/devices/platform/ocp/ocp*P8_43_pinmux/state

..but i did not investigate any further.

Regards

Klemen

[Charles Steinkuehler]

Glad it's working!

To use the config-pin utility you also have to load one of the universal
cape overlays (which will create the pinmux files in /sys/). It sounds
like you're making your own device-tree so you're fine. The universal
overlay files are for those who don't want to (or can't) create their
own device tree files.

--
Charles Steinkuehler
cha...@steinkuehler.net