RTOS/CC2650: SEnsor Controller Studio

Jorge Ribeiro36

Intellectual 520 points

Part Number: CC2650

Tool/software: TI-RTOS

Hi,

I'm using an ADT7311 to measure temperature. I'm programing the cc2650 with sensorcontroller studio.

Sometimes I measure 0, sometimes 128 ºC and sometimes the right temperature.

Any guess what is the problem?

I wrote the following code:

// Read the sensor1

spiBegin(SPI_POL1_PHA1, AUXIO_SPI_CSN_SS_TEMP1);

spiTx8bit(SPI_POL1_PHA1, 0x50);

spiRx16bit(SPI_POL1_PHA1; output.temp1);

spiEnd(SPI_POL1_PHA1, AUXIO_SPI_CSN_SS_TEMP1);

// Log the output data structure

rtlLogStructs(BV_RTL_LOG_OUTPUT);

// Notify the application

fwGenQuickAlertInterrupt();

// Schedule the next execution five RTC ticks from now

fwScheduleTask(2);

over 7 years ago

0 Severin Suveren over 7 years ago

TI__Mastermind 23730 points

Hi Jorge,

If you sometimes get a reading of 0 or 128, then it sounds like the sensor is to blame and not the Sensor Controller. Are you sure you are interfacing the temperature sensor correctly?

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

Hi Edvard,
I don't know how to control the time properly, can be that? And how can I do that?
Thanks

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

What kind of timing do you want?

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

I think the task doesn´t have enough time to read the value of temperature properly.
but I don't know how to change task time.

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

I'm not sure I follow you here. Not enough time during the SPI transfer? Or do you mean between SPI transfers?

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

In this case I need to send a message to adt7311 and it responds... I send always the same message and the repsponse varies ( 0ºC 128ºC or 28ºC (the right temperature). I think the comunication is not syncronized, i don't know if i'm being explicit enough.
Do you have any sugestion?

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

That has nothing to do with not being "fast" enough during the SPI transfer. The SPI Master, the Sensor Controller in this case, drives the speed for which the SPI transfer occurs at. Either the SPI slave, the temperature sensor, can keep up or it doesn't.

I hope you have read the ADT7311 datasheet. In the datasheet it looks like the maximum SPI bit rate it can support is 5 MHz. The maximum bit rate for the Sensor Controller SPI controller is 2 MHz, so that is no problem. So, what is a likely reason you are receiving weird samples is that you are reading a sample from the sensor before the sample is ready. The datasheet says it takes approx. 240 ms to complete a sample, so if you try to read the sample at a faster rate than 240 ms then you will receive weird data.

Again, I hope you have read the ADT7311 datasheet.

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

I read the datasheet, but how i control that time in sensor controller studio?
thanks

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

That depends. Are you reading the temperature sensor in an Execution Code and using RTC scheduling?

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

Yes, i think. I need to be honest I'm learning to use sensor controller.... i post my code in the first coment.
Thanks

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

If you are using RTC scheduling, make sure you don't schedule your SC task at a faster rate than 240 ms based on what you configure the RTC ticks to. If this doesn't make much sense, I suggest to go through the SimpleLink Academy labs for the Sensor Controller, starting with the Fundamentals lab.

Sensor Controller Fundamentals: dev.ti.com/.../sc_01_basic.html

0 Jorge Ribeiro36 over 7 years ago in reply to Severin Suveren

Intellectual 520 points

Hi Edvard,
I'm sorry for molest you, but i read the fundamentals of sensor controller and in that page said that 1 RTC tick was 125 ms. So I programmed the cc2650 with 2 RTC ticks (more than 240 ms) and I have the same problem. Any guess?
Thanks

0 Severin Suveren over 7 years ago in reply to Jorge Ribeiro36

TI__Mastermind 23730 points

Hi Jorge,

The RTC does not have any default tick configuration. If you are testing your SC project in SCS, then this is configured in the Preferences page in SCS. If you are testing your SC project in an application, then this is configured with either scifStartRtcTicks() or scifStartRtcTicksNow(). Depending on what you configure it to be, make sure that the RTC scheduling in your SC task doesn't exceed 240 ms.

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RTOS/CC2650: SEnsor Controller Studio