DRA80M: DRA80M - Reading the temperature data from the VTM_TMPSENSE0_STAT register

Hi Vencatesh,

can you try to reattach the image?

regards,

Yordan

Hi Venkatesh,

I don't know the VTM programming. Just wanted to suggest you to look at the control register bits at offset 80h.

At least, I can see the bit [6] CLRZ is 0, which means temp monitor outputs are currently reset.

You may also try to set bit [5] SOC to 1 for ADC Start-of Conversion.

As I can understand, normally the VTM module is controlling the sensors and generates overtemperature alerts automatically, once configured by software. A top-level VTM programming is provided in section 5.2.2.1.5.3.4 VTM Programming Model

Regards,

Stan

Hi Stan,

I did follow your recommendation

i.e., Setting the control register bit [6] CLRZ to 1 and bit [5] SOC to 1. 42050080 is set as 00000061. Refer attachment.

With the above change I read the temp ADC code value as 1023 which is outside the range or the response I got is 7FF/ 3FF (the EOCZ is toggling) from 42050088.

I am running the module at ambient. Please let me know what else I need to configure to get the appropriate ADC code or is there a test script you can provide? I have a Lauterbach debugger and can feed the register information as per your suggestion.

1. Please set also bit [7] CLKON_REQ.

2. Clear bit [0] CBIASSEL  to select bandgap voltage as reference

Please perform steps one by one. Allow some time to pass and refresh the DTEMP after each step.

Regards,

Stan

Also, I found the following in a recent spec update:

"Prior to each single shot sampling, software is expected to reset the sensor's STAT eoc_fc_update field via the sensor's CTRL clrz functionality. Likewise, software is expected to perform the sensor reset prior to transitioning from single shot sampling mode to continuous sampling mode."

Hi Stan,

I see a response from the temperature sensor after setting the bit [7]  CLKON_REQ and clearing bit [0] CBIASSEL. See below. I see the conversion also make sense. I read 50-52C at ambient (22C)

I am not sure what exactly software needs to do in the ctrl register to reset the EOC_FC_UPDATE. Are you saying software to drive E0( as above) value in the control register every time  to read the temperature value?Please elaborate.

I also have few questions

1) Does the internal temperature sensor requires calibration? I don't see it in the User manual

2)Also how accurate the reading is? Should we need to provide any offset values etc.,.?

3) Is there a minimum time I need to wait to get the appropriate temperature reading after the processor boots up?

Thankyou.

I'm glad you managed to get a dtemp result.

Regarding the temp sensor reset:

Reset Sensors Sequence:
1. Set the WKUP_VTM_TMPSENS_CTRL_j[6] CLRZ bit to enable the sensor (so that it has the ENA
input high).
2. Wait for 900ns to 1us for the sensor clock to toggle and register the updated ENA pin.
3. Clear WKUP_VTM_TMPSENS_CTRL_j[6] CLRZ to disable and reset the sensor (as it requires an
ENA transition from 1 to 0 to reset initially) .
4. Wait for 900ns to 1us for the sensor clock to toggle and register the updated ENA pin.
5. Now the sensor can be configured and enabled normally.

Regarding your questions 1-3:

1. Sensor readings can be fine-tuned  via TRIM registers at offset 4h for each sensor.

2. This is not specified in the datasheet. Will check internally.

3. The only time delay specified is between the temp sensor register accesses. It is 1 us as shown in the sequence above. The other delay will come with the waiting for EOCZ to become 0 (end-of-conversion).

regards,

Stan

Hi Stan,

Thanks for your response.

 I was able to read the temperature in continuous sampling mode. If I understand correctly then software need to reset the sensor sequence as below

1. Set the VTM_TMPSENSx_CTRL_j[6] => CLRZ to '0'

2. Wait for 1us

3.  Set the VTM_TMPSENSx_CTRL_j[6] => CLRZ to '1'

4. Wait for 1us

5. Configure the VTM_TMPSENS_CTRL as 0x000000E0 and read the VTM_ TMPSENSx_STAT.

Regarding your questions 1-3:

1. Sensor readings can be fine-tuned  via TRIM registers at offset 4h for each sensor.

- After reading the VTM_TMPSENS0_TRIM. There are trim settings for few parameters like slope error, offset error, slope of output voltage of bandgap, offset in output voltage of bandgap. I am not sure how to determine these trim values to compensate for the internal temperature sensor!. Are you suggesting to include 0x00000100 in the respective TRIM register? Please clarify

2. This is not specified in the datasheet. Will check internally.

- Okay. Please check and let us know.

3. The only time delay specified is between the temp sensor register accesses. It is 1 us as shown in the sequence above. The other delay will come with the waiting for EOCZ to become 0 (end-of-conversion).

- Is it something you can estimate the wait time for EOCZ to become 0 or is it a question to the software group?

Hi Stan,

The below statement is for an external sensor and not for the on die sensor?

"Sensor readings can be fine-tuned  via TRIM registers at offset 4h for each sensor".

Please clarify.

Thanks and regards,

Venkatesh