I just compiled devmem2 from source and your script is reading from memory
correctly now. But the second read is returning 0x00 and it still can't find
that directory.

 

From: Junkytomato [mailto:junkytom...@hotmail.com] 
Sent: Saturday, November 30, 2013 4:30 PM
To: beagleboard@googlegroups.com
Subject: RE: [beagleboard] Temperature Sensor in my BBB

 

I just tried to run your script on my BBB (running Debian) and it came up
with a few errors:

*         Devmem2 is not installed. I would assume that this is some sort of
a utility to read from memory? How can I install it?

*         The directory '44e10448.bandgap' doesn't exist. Is there something
that I have to mount manually?

 

 

From: beagleboard@googlegroups.com <mailto:beagleboard@googlegroups.com>
[mailto:beagleboard@googlegroups.com] On Behalf Of William Pretty Security
Sent: Saturday, November 30, 2013 11:26 AM
To: beagleboard@googlegroups.com <mailto:beagleboard@googlegroups.com> 
Subject: RE: [beagleboard] Temperature Sensor in my BBB

 

No. But if room temp is about 20C then that's 28C above room temp .

 

 

From:  <mailto:beagleboard@googlegroups.com> beagleboard@googlegroups.com [
<mailto:beagleboard@googlegroups.com> mailto:beagleboard@googlegroups.com]
On Behalf Of Maxim Podbereznyy
Sent: Saturday, November 30, 2013 2:18 PM
To: beagleboard
Subject: Re: [beagleboard] Temperature Sensor in my BBB

 

48 degrees is not enough to hurt your finger

 

2013/11/30 Mark A. Yoder <mark.a.yo...@gmail.com
<mailto:mark.a.yo...@gmail.com> >

Indeed there is a temp sensor.  I looked in up in the TRM and then wrote
this script to read it.

 

#!/bin/bash

# Reads internal temperature of AM335x

# 0x44e1_0000 is the starting address of the Control Module (Table 2.2 p 171
of TRM)

# 0x0448 is the address of the bandgap_crtl register which has 

#           8 bits (8-15) of temperature (Table 9-19 p 1137)

devmem2 0x44e10448 w

devmem2 0x44e10449 b

cat /sys/devices/ocp.2/44e10448.bandgap/temp1_input

 

/dev/mem opened.

Memory mapped at address 0xb6ff5000.

Read at address  0x44E10448 (0xb6ff5448): 0x0000301E

/dev/mem opened.

Memory mapped at address 0xb6f71000.

Read at address  0x44E10449 (0xb6f71449): 0x30

48000

 

I used devmem2 to read the register directly.  The last command uses the
Linux interface to read it.  I'm guessing the units are C, but the manual
doesn't say.

 

--Mark


On Friday, November 29, 2013 4:27:01 PM UTC-5, Gerald wrote:

Technical Reference Manual. It can be found at the link I sent you.

 

"You can read about it in the TRM found at
<http://www.ti.com/product/am3359> http://www.ti.com/product/am3359";

 

It describes how the processor works and all the functions of the processor.
It has all the addresses for all the internal components. Just do a search
for Temperature sensor.

 

Gerald

 

On Fri, Nov 29, 2013 at 3:23 PM, Junkytomato <junky...@hotmail.com
<mailto:junky...@hotmail.com> > wrote:

Maybe I should have asked this originally. What does 'TRM' mean?

 

From:  <mailto:beagl...@googlegroups.com> beagl...@googlegroups.com [
<mailto:beagl...@googlegroups.com> mailto:beagl...@googlegroups.com] On
Behalf Of Gerald Coley


Sent: Friday, November 29, 2013 1:12 PM

To: beagl...@googlegroups.com <mailto:beagl...@googlegroups.com> 


Subject: Re: [beagleboard] Temperature Sensor in my BBB

 

I do not know how to access it. You can read the TRM and see if there is a
mechanism for accessing it and if so, what the address is.

 

Gerald

 

 

On Fri, Nov 29, 2013 at 3:01 PM, <junky...@hotmail.com
<mailto:junky...@hotmail.com> > wrote:

It doesn't seem to be my finger heating it up; it hurts after half a second
or so, and I don't think that the human body temperature is enough to hurt
the human body, generally speaking ;). Anyway, do you know how I can access
it? I have a few packages that should be able to read built-in temperature
sensors, but none of them are able to locate it automatically and I have no
idea what to give it for 'Sensor location'. I don't see anything mounted in
/dev/ that could be helpful and I don't know enough about Linux to know
where else it could be. What is the 'location' that I need to access it?



On Friday, November 29, 2013 2:27:17 PM UTC, Gerald wrote:

That is normal operation. When you hold your finger on it your skin heats up
making it hot The longer you hold it, the hotter it feels.

 

The processor has on on-chip temperature sensor. You can read about it in
the TRM found at http://www.ti.com/product/am3359

 

Gerald

 

On Fri, Nov 29, 2013 at 12:49 AM, <junky...@hotmail.com
<mailto:junky...@hotmail.com> > wrote:

I was using my BBB recently and noticed that it gets pretty hot when it runs
for more than a few minutes (I've never really touched it while it's on
before). It doesn't seem to be a problem, but I was wondering if the BBB had
a built-in temperature sensor. I know some laptops have internal
thermometers, so does the BBB have one? It's meant as a minimal device, so I
would imagine it doesn't, but it would be nice to know if it does!

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