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 
> <[email protected]<javascript:>
> > wrote:
>
>> Maybe I should have asked this originally… What does ‘TRM’ mean?
>>
>>  
>>
>> *From:* [email protected] <javascript:> [mailto:
>> [email protected] <javascript:>] *On Behalf Of *Gerald Coley
>> *Sent:* Friday, November 29, 2013 1:12 PM
>> *To:* [email protected] <javascript:>
>> *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, <[email protected] <javascript:>> 
>> 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, <[email protected]> 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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