48 degrees is not enough to hurt your finger

2013/11/30 Mark A. Yoder <[email protected]>

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