I've been walking through the GPIO pins for expansion header P8 on a
Beaglebone Black, checking actual pin output with the hardware [1] [2]
information. Pins 3 through 46 on P8 are listed in the hardware
information as available for GPIO. Indeed, I can set any of them but
I notice that on pins 25 (gpio1_0), 21 (gpio1_30), and 20 (gpio1_31)
seem to be reserved by OpenBSD and great trouble is caused if I try to
set them with gpioctl(8) like I would for any other pin, e.g. like pin
46 here:
/usr/sbin/gpioctl gpio2 7 set out p8pin46;
Trial and error shows that setting pins 25, 21, and 20 causes trouble
right away. I've looked in INSTALL.armv7 and the GPIO-related manual
pages. Are there other pins in use by the system which are less
immediate in making their effects known? I don't want to let the magic
blue smoke out of any hardware components.
How can I find all pins are reserved by OpenBSD and should not be
changed or used?
Of the pins reserved, what are their purposes?
Regards,
Lars
[1] Figure: "65 Possible Digital I/Os" http://beagleboard.org/Support/bone101
[2] Table 10. "P8 Mux Options Modes 4-7" BONE_SRM.pdf
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OpenBSD 6.0-current (GENERIC) #11: Mon Aug 8 21:05:56 MDT 2016
dera...@armv7.openbsd.org:/usr/src/sys/arch/armv7/compile/GENERIC
real mem = 536870912 (512MB)
avail mem = 517963776 (493MB)
mainbus0 at root: TI AM335x BeagleBone Black
cpu0 at mainbus0: ARM Cortex A8 R3 rev 2 (ARMv7 core)
cpu0: DC enabled IC enabled WB disabled EABT branch prediction enabled
cpu0: 32KB(64b/l,4way) I-cache, 32KB(64b/l,4way) wr-back D-cache
omap0 at mainbus0
prcm0 at omap0 rev 0.2
sitaracm0 at omap0: control module, rev 1.0
omap0: device edma unit 0 not configured
dmtimer0 at omap0 rev 3.1
dmtimer1 at omap0 rev 3.1
omgpio0 at omap0: rev 0.1
gpio0 at omgpio0: 32 pins
omgpio1 at omap0: rev 0.1
gpio1 at omgpio1: 32 pins
omgpio2 at omap0: rev 0.1
gpio2 at omgpio2: 32 pins
omgpio3 at omap0: rev 0.1
gpio3 at omgpio3: 32 pins
simplebus0 at mainbus0: "ocp"
simplebus1 at simplebus0: "l4_wkup"
simplebus2 at simplebus1: "scm"
intc0 at simplebus0 rev 5.0
com0 at simplebus0: ti16750, 64 byte fifo
com0: console
tiiic0 at simplebus0 rev 0.11
iic0 at tiiic0
"ti,tps65217" at iic0 addr 0x24 not configured
"at,24c256" at iic0 addr 0x50 not configured
"nxp,tda998x" at iic0 addr 0x70 not configured
tiiic1 at simplebus0 rev 0.11
iic1 at tiiic1
"at,24c256" at iic1 addr 0x54 not configured
"at,24c256" at iic1 addr 0x55 not configured
"at,24c256" at iic1 addr 0x56 not configured
"at,24c256" at iic1 addr 0x57 not configured
ommmc0 at simplebus0
sdmmc0 at ommmc0: 1-bit, mmc high-speed
ommmc1 at simplebus0
sdmmc1 at ommmc1: 1-bit, mmc high-speed
omdog0 at simplebus0 rev 0.1
cpsw0 at simplebus0: version 1.12 (0), address 68:9e:19:8f:85:fa
ukphy0 at cpsw0 phy 0: Generic IEEE 802.3u media interface, rev. 1: OUI 0x0001f0
, model 0x000f
sdmmc0: can't enable card
scsibus0 at sdmmc1: 2 targets, initiator 0
sd0 at scsibus0 targ 1 lun 0: <Kingston, S10004, 0000> SCSI2 0/direct fixed
sd0: 3648MB, 512 bytes/sector, 7471104 sectors
vscsi0 at root
scsibus1 at vscsi0: 256 targets
softraid0 at root
scsibus2 at softraid0: 256 targets
boot device: sd0
root on sd0a (d499bd6a7c8df27c.a) swap on sd0b dump on sd0b
WARNING: CHECK AND RESET THE DATE!
