TS-4710 NVRAM: Difference between revisions

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(Created page with "The RTC has an included 1KB NVRAM which can be accessed using tshwctl. <source lang=bash> tshwctl --nvram </source> This will return a format such as: nvram0=0xf7f8a73e ...")
 
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The RTC has an included 1KB NVRAM which can be accessed using tshwctl.
The RTC has an included 128-byte battery-backed NVRAM which can be accessed using tshwctl.  Its contents will remain with the main power off, so long as the RTC battery is installed and withing a valid voltage range.


<source lang=bash>
<source lang=bash>
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   nvram31=0x70544510
   nvram31=0x70544510


This breaks up the NVRAM into 32x 32-bit registers which can be accessed in bash.  As this uses the name=value output, you can use "eval" for simple parsing:
This breaks up the NVRAM into 32 32-bit registers which can be accessed in bash.  As this uses the name=value output, "eval" can be used for simple parsing:
<source lang=bash>
<source lang=bash>
eval `tshwctl --nvram`
eval `tshwctl --nvram`
Line 18: Line 18:
</source>
</source>


From the above value, this would return 0x48ca4278.  To set values, you can use environment variables:
From the above value, this would return 0x48ca4278.  To set values, the respective environment variable name can be set:
<source lang=bash>
<source lang=bash>
nvram0=0x42 ts4700ctl --nvram
nvram0=0x42 tshwctl --nvram
</source>
</source>


If you read back nvram0, this should now confirm the value is 0x42.
Note that the command 'tshwctl --nvram' will output the current contents of NVRAM before setting any new values.  At this point, running 'tshwctl --nvram' once more will print the updated contents for verification.  This can be used for  reading a 32-bit quantity and updating it with a single command.

Latest revision as of 16:56, 2 April 2018

The RTC has an included 128-byte battery-backed NVRAM which can be accessed using tshwctl. Its contents will remain with the main power off, so long as the RTC battery is installed and withing a valid voltage range. 

tshwctl --nvram

This will return a format such as: 

 nvram0=0xf7f8a73e
 nvram1=0x2fef5ae0
 nvram2=0x48ca4278
 ...
 nvram31=0x70544510

This breaks up the NVRAM into 32 32-bit registers which can be accessed in bash. As this uses the name=value output, "eval" can be used for simple parsing: 

eval `tshwctl --nvram`
echo $nvram2

From the above value, this would return 0x48ca4278. To set values, the respective environment variable name can be set: 

nvram0=0x42 tshwctl --nvram

Note that the command 'tshwctl --nvram' will output the current contents of NVRAM before setting any new values. At this point, running 'tshwctl --nvram' once more will print the updated contents for verification. This can be used for reading a 32-bit quantity and updating it with a single command.

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