Watchdogs and MICOM on A series(SH4) - Revision history

Tom van at 11:34, 10 February 2013

2013-02-10T11:34:45Z

Tom van: add umicom.img

2013-02-10T11:03:04Z

add umicom.img

Tom van at 12:40, 11 May 2011

2011-05-11T12:40:25Z

Tom van: /* Micom periodic watchdog */

2011-05-01T11:32:01Z

‎Micom periodic watchdog

Tom van: Created page with 'There is abundant use of watchdogs/timeouts in LE46A956. I'm not sure if it is because of "quality" of firmware or it is an anti-hacking measure. Micom is a microcontroller respâ¦'

2011-05-01T11:30:50Z

Created page with 'There is abundant use of watchdogs/timeouts in LE46A956. I'm not sure if it is because of "quality" of firmware or it is an anti-hacking measure. Micom is a microcontroller respâ¦'

New page

There is abundant use of watchdogs/timeouts in LE46A956. I'm not sure if it is because of
"quality" of firmware or it is an anti-hacking measure.

Micom is a microcontroller responsible for receiving commands from RC,
switching main power supply on and off, resetting main SH4 CPU and so on.
It also works as a watchdog.
Use
/mtd_boot/MicomCtrl
or
/lib/modules/MicomCtrl
to send commands to Micom. If the main tv process exeDSP is active, a collision between MicomCtrl and exeDSP command can happen - you can repeat MicomCtrl several times to ensure the command is accepted.

== Early boot timeout ==
In the first 14 seconds since boot start Micom expects command Set_Sw_Pvcc (208).
exeDSP sends it normally. If you don't want to or can't run exeDSP, use
/mtd_boot/MicomCtrl 208
If this command is not given in time, TV reboots 6 times and after that this watchdog
deactivates itself.

== Boot finished OK timeout ==
Micom expects command SetAppInitOk in 60 seconds from boot start otherwise it reboots.
/mtd_boot/MicomCtrl 232 1

== Micom periodic watchdog ==
Periodic WD if disabled in boot time. exeDSP always enables it during startup and then periodically sends alive message. Timeout is 40 seconds.
Commands:
/mtd_boot/MicomCtrl 22 # watchdog enable
/mtd_boot/MicomCtrl 23 # watchdog disable
/mtd_boot/MicomCtrl 24 # alive message

/mtd_boot/MicomCtrl 133 1/0 # watchdog on/off
/mtd_boot/MicomCtrl 135 # get watchdog on/off
hexdump -v -n 9 -e '/1 "%02x "' /dev/ttyAS2 # reads reply packet from serial line

== Linux kernel watchdog ==
Software watchdog with 30 second timeout and /proc/watchdog interface.
Probably only this one can be switched off in service menu.

== exeDSP internal watchdog ==
One thread of exeDSP periodically checks the other important threads and if one does not respond, reboots the TV.
Watchdog thread can be disabled writing nonzero to address 0x2091164.

== Other Micom commands ==
/mtd_boot/MicomCtrl 18 # power off
/mtd_boot/MicomCtrl 29 # system restart (cycles main power off and on)
/mtd_boot/MicomCtrl 143 # CPU reset (TV screen is shifted because GPU is not properly initialized)

/mtd_boot/MicomCtrl 227 0-4 # power LED control 0..off, 1/2/3..slow/medium/fast flashing, 4..on

@@ Line 18: / Line 18: @@
 It should work on all models with T-RBYDEUC software a might run also on other SH4 models. Grab latest version and source from [http://download.samygo.tv/A%20Series/ download area].
-Export the image from a nfs server or set up tftp server. Lets suppose we have '''umicom.img''' on a linux host in directory /home/samygo/
+Export the image from a nfs server or set up a tftp server. Lets suppose we have '''umicom.img''' on a linux host in directory /home/samygo/
   sudo exportfs ''ip_of_your_tv'':/home/samygo
-At TV U-Boot prompt enter
+At TV U-Boot prompt enter:
   nfs 84300000 ''ip_of_your_linux_host'':/home/samygo/umicom.img;bootm
@@ Line 39: / Line 39: @@
   Bytes transferred = 70548 (11394 hex)
-umicom.img without parameters switch off Micom watchdogs and reset ''silent'' flag. Power LED starts quickly flashing to indicate that communication works. A short help is printed
+umicom.img without parameters switch off Micom watchdogs and reset ''silent'' flag. Power LED starts quickly flashing to indicate that communication works. A short help is printed:
   STi710x> bootm

@@ Line 2: / Line 2: @@
 "quality" of firmware or it is an anti-hacking measure.
-Micom is a microcontroller responsible for receiving commands from RC,
+== Micom microcontroller ==
 switching main power supply on and off, resetting main SH4 CPU and so on.
 It also works as a watchdog.
 Use
   /mtd_boot/MicomCtrl
@@ Line 10: / Line 13: @@
   /lib/modules/MicomCtrl
 to send commands to Micom. If the main tv process exeDSP is active, a collision between MicomCtrl and exeDSP command can happen - you can repeat MicomCtrl several times to ensure the command is accepted.
 == Early boot timeout ==

@@ Line 34: / Line 34: @@
 == Linux kernel watchdog ==
-Software watchdog with 30 second timeout and /proc/watchdog interface.
+Software watchdog with 30 second timeout and /proc/watchdog interface. /proc/watchdog is periodically written from exeDSP internal watchdog thread.
 == exeDSP internal watchdog ==
 One thread of exeDSP periodically checks the other important threads and if one does not respond, reboots the TV.
-Watchdog thread can be disabled writing nonzero to address 0x2091164.
+Watchdog thread can be disabled writing nonzero to address 0x2091164. If the watchdog thread is disabled, /proc/watchdog is not synced anymore.
 == Other Micom commands ==