TMS570LC4357 - internal temperature sensors

Jiri,

"I understood that AD2 has up to 24 channels" 

ADC2 has 25 external channels 0 to 24
Internally, channels 30 and 31 are used by 2 of the 3 temperature sensors. (The 3 temperature sensor is multiplexed with ADC1 channel 31.

In the TRM, it is specified that the 3 temperature sensors are enable by a single bit PINMMR174[24] = 0

For this reason, the following code makes sense:

pinMuxReg->PINMUX[174] &= 0XFEFFFFFFU;
PINMUX_TEMP1_ENABLE(ON);
PINMUX_TEMP2_ENABLE(OFF);
PINMUX_TEMP3_ENABLE(OFF);

pinMuxReg->PINMUX[174] &= 0XFEFFFFFFU;
PINMUX_TEMP1_ENABLE(ON);
PINMUX_TEMP2_ENABLE(ON);
PINMUX_TEMP3_ENABLE(ON);

Please let me know if I have clarify the situation.

Jean-Marc,

in other words, if the sensors 2 and 3 are activated there are all user ADC inputs available for a user (outer) measurement. If the sensor 1 is activated, the internal ADC input  ADC1IN[31] is reserved for the inner measurement (of the internal temperature). OK :-)

Another question - all three sensors are measuring the same temperature - so-called "the internal junction temperature", right? I would understand a reason of redundat measurement.

What is behind my question? I do not want to occupy the ADC1IN[31] input by the connected internal sensor 1 - it will be used for measuring external signals.

But, of course, I can follow this way only if I am sure that the measurements by means of the sensors 2 and 3 provide the same temperature as the sensor 1 would.

Thanks a lot,

Best regards,

Jiri

Dear Jean-Marc,

please may you comment my last question?

Thanks a lot in advance,

Best regards, Jiri

Jiri,


Sorry for this late answer.

Temp Sensor 3 is located in the middle of the die and mainly monitor the temperature around the dual core.

Temp Sensor 1 and 2 are located close by the complex I/Os (ADC1 and ADC2)

The reason why we have these 3 options is to provide better availability in your system.

We recommend using Sensor 3, it is dedicated on ADC2 and will not remove any external ADC input.

Also we are working on an application note to explain and describe the best use of these temp sensors. This application note should be ready by end of November.

Any update on the new application note?  I'm seeing some weird behavior that may be related.

With the pinmux configured with Temperature 1 disabled, using a 5V analog power supply and reference, and presenting a 3.3V signal to ball T13, I actually read about 95% of full scale instead of the expected 67% of full scale.  All other ADC input pins read normally.  Explicitly enabling the Temperature 1 channel instead also reads normally.

Any ideas?