[Gumstix-users] Overo temperature sensor?

[etd083 <et...@ve...>]

I have read the posts in this forum about the temperature sensor on the Overo
COM boards and being able to get the temperature in degrees C from the
/sys/devices/platform/omap34xx_temp/temp1_input file.  My assumption is that
the driver "omap34xx_temp" is used to interface with the temperature sensor. 
However when I look at the code for this driver, it references the define
OMAP343X_CONTROL_TEMP_SENSOR which I believe is supposed to point to a
general control register for the temperature sensor.  This define is equal
to OMAP2_CONTROL_GENERAL + 0x2b4 = 0x270 + 0x2b4 = 0x524.  Thus 0x524 should
be the offset to the physical address of the general control register for
controling the temperature sensor.  However when I look in the OMAP35x
Applications Processor TRM for the System Control Module, there is no
definition for controlling a temperature sensor in the general control
registers.  There is no definition for anything at address offset 0x2b4 or
physical address offset 0x524 (0x4800 2524).

In the OMAP34xx TRM (swpu114.pdf) for the System Control Module there is a
CONTROL_TEMP_SENSOR (page 924) at address offset 0x2b4 and physical address
offset 0x524 (0x4800 2524).  This definition is consistent with the code for
the driver "omap34xx_temp".  There is also an entire section discussing the
temperature sensor on page 785.  So my question is, is the
CONTROL_TEMP_SENSOR register supported by the OMAP35x processors or is it a
leftover from the OMAP34x processors?  If there is a temperature sensor on
the board (where is it), is this the right driver for it?

I was questioning the temperature sensor functionality because as others
pointed it it does not appear to work properly.  That is I have observed
inconsistent results where sometimes the temperature goes up, but then if I
power off heat producers such as the wi2wi, the temperature never goes back
down according to the driver temp1_input file.  However if I feel with my
finger the wi2wi and processor are no longer hot to the touch.  I have
waited a half hour which should be plenty of time for the heat to dissipate.

We are in the process of building a custom daughter board and have trying to
determine if there really is temperature sensor functionality on the Overo
COM.  If there isn't, then we are going to put our own temperature sensor on
our custom board.  So if anyone has a more definitive answer on this I would
appreciate it.  Thanks!!!!
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