AM335X- how to enable soc-die temperature sensor on SDK8.0

Joe Chen3

Dears,

Our have a requiement for soc-die temperature sensor to monitor CPU temperature,

1. I find the wiki processors.wiki.ti.com/.../AM335x_EVM_On-Board_Components_Drivers_Guide,

but I can't make sure the sheet that is soc-die temperature sensor.

I reference the sheet to enable lm75 driver, but the driver seem can't workable.

root@am335x-evm:~# cd /sys/bus/i2c/drivers/lm75/
root@am335x-evm:/sys/bus/i2c/drivers/lm75# ls
bind uevent unbind
temp1_input-evm:/sys/bus/i2c/drivers/lm75# cat /sys/bus/i2c/drivers/lm75/2-0048/
cat: can't open '/sys/bus/i2c/drivers/lm75/2-0048/temp1_input': No such file or directory
root@am335x-evm:/sys/bus/i2c/drivers/lm75#

Please provide the suggestion for the question, thanks.

B.R.

Joe

over 9 years ago

0 Yordan Kovachev over 9 years ago

TI__Guru**** 161600 points

Hi Joe,

Just a clarification lm75 driver is used for the on-board temperature sensor for monitoring the temperature of AM335x EVM, not the AM335x SoC itself.

A couple of questions:
1. Are you using the AM335x EVM? the guide you reference is for the EVM (not the starter kit or beaglebone or a custom board).
2. What is the content of /sys/bus/i2c/drivers/lm7 ?

Best Regards,
Yordan

0 Joe Chen3 over 9 years ago in reply to Yordan Kovachev

Intellectual 480 points

Hi Yordan,

You are right that lm75 driver is used for the on-board temperature sensor after I check the AM335x EVM Schematic.
Could you provide the AM335x SoC its temperature sensor information or AM335x SoC doesn't on-die temperature sensor?

B.R.
Joe

0 Yordan Kovachev over 9 years ago in reply to Joe Chen3

TI__Guru**** 161600 points

Hi Joe,

Check the bandgap_ctrl & bandgap_trim registers in AM335x TRM. See 9.3.1.9 bandgap_ctrl Register (offset = 448h) [reset = 0h] & 9.3.1.10 bandgap_trim Register (offset = 44Ch) [reset = 0h]. Also check the following e2e threads:
e2e.ti.com/.../393235
e2e.ti.com/.../232759

The bandgap temp sensor is enabled by setting bandgap_ctrl[bit 5]= 0x0 & bandgap_ctrl[bit 6]= 0x0. Temperature values can be read from bandgap_ctrl[15:8].

Best Regards,
Yordan

0 Joe Chen3 over 9 years ago in reply to Yordan Kovachev

Intellectual 480 points

Hi Yordan,

Thank your help, do the SDK8.0 have any command for writing/reading bandgap_ctrl.

B.R.
Joe

0 Yordan Kovachev over 9 years ago in reply to Joe Chen3

TI__Guru**** 161600 points

Hi Joe,

You can use the devmem2 command to read/write registers from user space.

Best Regards,
Yordan

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AM335X- how to enable soc-die temperature sensor on SDK8.0