On Mon, 17 May 2021 07:50:02 -0700 (PDT), in
gmane.comp.hardware.beagleboard.user Bruce Chidester
<[email protected]> wrote:
>This leaves me with a total memory of 28K. Storing float's I can store
>7,168 values. I would like to capture 20,000 values in about 250ms.
Capture from what?
80 samples/msec... or 80000 per second. If I converted properly, about
0.0125msec per sample.
>
>The Derek Malloy tutorial on PRU's (
>http://exploringbeaglebone.com/chapter15/) claims, "a pool of 2,000,000
>bytes is allocated for the sample data". Things appear to have changed
>since the writing of that tutorial. No more dynamic Device Tree through UIO
The tutorial you reference is based upon the FIRST EDITION of the book
"Additional Content for First Edition" (when it was chapter 13).
>and PRU's accessed through Remote Proc. Not sure if the architecture
Device trees are now loaded by u-Boot. If you really want UIO, there is
a device tree for that... By default, current images use the TI recommended
RPROC/msg system (partly because that is supposed to work with multiple
types of special processor cores -- the BB AI not only has PRU, but DSP
processors).
Extract from /boot/uEnv.txt:
###PRUSS OPTIONS
###pru_rproc (4.14.x-ti kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-14-TI-00A0.dtbo
###pru_rproc (4.19.x-ti kernel)
uboot_overlay_pru=/lib/firmware/AM335X-PRU-RPROC-4-19-TI-00A0.dtbo
###pru_uio (4.14.x-ti, 4.19.x-ti & mainline/bone kernel)
#uboot_overlay_pru=/lib/firmware/AM335X-PRU-UIO-00A0.dtbo
###
You would have to uncomment the UIO line, and comment out the active
RPROC line (only one mode allowed at a time); then reboot.
>changed as well. This makes most of the printed material out of date
>concerning PRU's and it's painful to figure out what is current and not. I
>would love to have these 2,000,000 bytes available in the new architecture.
Note that those bytes are allocated in the DDR RAM. There is no
hardware change.
>Needing help with the addressing, and some code samples would be excellent.
>Hoping someone out there can help me get it.
>
Might https://github.com/pgmmpk/bbb_pru_adc be of use? Note that the
maximum speed for that code is 15KHz, or just 1/5th of your 80KHz desire.
--
Dennis L Bieber
--
For more options, visit http://beagleboard.org/discuss
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