TMAG5170-Q1: TMAG5170 - SDO/SDI idle state

Hubert S

Part Number: TMAG5170-Q1
Other Parts Discussed in Thread: TMAG5170

Hi,

I want to ask about SDO/SDI idle states. In my configuration SDO is low when there is no communication. The only exception is situation when there is wakeup request signalised with ALERT pin. Communication with TMAG starts and for some reason SDO is in high state. Is it possible that there is some weak pull up on TMAG's side?

I receive correct results and so on but I don't understand why there is this exception.

5 months ago

0 Scott Bryson 5 months ago

TI__Mastermind 24420 points

Hubert,

I have reached out to see if I can get more detail about this. While we look into it, would you be able to provide your register settings?

Thanks,

Scott

0 Hubert S 5 months ago in reply to Scott Bryson

Prodigy 20 points

Scott,

Below you can find the configuration used before and just after wakeup.

xx - depends on external state

TEST_CONFIG	0x0F	0x00	0x50	0x04
MAG_GAIN_CONFIG	0x11	0x00	0x00	0x00
SENSOR_CONFIG	0x01	0x11	0x40	0x00
SYSTEM_CONFIG	0x02	0x00	0x25	0x02
X_THRX_CONFIG	0x04	xx	xx	xx
Y_THRX_CONFIG	0x05	xx	xx	xx
Z_THRX_CONFIG	0x06	xx	xx	xx
ALERT_CONFIG	0x03	0x10	0x05	0x01
DEVICE_CONFIG	0x00	0x01	0x48	0x13

Sleep

...

TMAG_ALERT

DEVICE_CONFIG	0x00	0x31	0x38	0x05
AFE_STATUS	xx	xx	xx	xx
SYS_STATUS	xx	xx	xx	xx

0 Scott Bryson 4 months ago in reply to Hubert S

TI__Mastermind 24420 points

Hubert,

It looks like you are using ALERT as a switch mode output, but in your description am I understanding that you are driving ALERT to wake the device? Or is it that the idle state changes when TMAG5170 crosses switch mode outputs?

Thanks,

SCott

0 Hubert S 4 months ago in reply to Scott Bryson

Prodigy 20 points

Using pin ALERT, the TMAG wakes the main ECU when there is a change in the magnetic field that crosses the thresholds.

0 Scott Bryson 4 months ago in reply to Hubert S

TI__Mastermind 24420 points

I'm working to discuss this with our team, so far I haven't seen anything to suggest why you are observing this. When I test on my PCB, I consistently see this idle at a low Voltage for both ALERT low and high output. Is there any chance that the MCU is pulling up this pin when idle, but changing the IO state of the pin when the ALERT toggles?

We will continue to look into this as we can over the next week, but I do want to make you aware that we may not be able to respond as frequently due to the Thanksgiving holiday.

Thanks,

Scott

0 Hubert S 4 months ago in reply to Scott Bryson

Prodigy 20 points

I checked this on my end, but I couldn't find a reason for it to behave like this. I will try again.

I understand, no worries, thank you for the information.

0 Alicia Rosenberger 4 months ago in reply to Hubert S

TI__Genius 16895 points

Hi Hubert,

Would you be able to share the schematic of the board you are testing this out on? Specifically, with relation to the SDO pin. We are trying to see if we can replicate this behavior in simulation, so we would like to know if there are any differences in your setup compared to ours.

Best,

~Alicia

0 Hubert S 4 months ago in reply to Alicia Rosenberger

Prodigy 20 points

Hi Alicia,

I'll check one more thing on my side and let you know if I find anything. It will take me a few days, so I will get back to you no later than the beginning of next week.

0 Alicia Rosenberger 4 months ago in reply to Hubert S

TI__Genius 16895 points

Hi Hubert,

Thanks for letting me know.

Best,

~Alicia

0 Hubert S 4 months ago in reply to Alicia Rosenberger

Prodigy 20 points

Hi Alicia,

I have looked into what is happening there in detail, and it is not a TMAG fault, so we can close this topic.

The issue lies with the HW SPI on my MCU.

+1 Scott Bryson 4 months ago in reply to Hubert S

TI__Mastermind 24420 points

Hubert,

Thanks for double checking and letting us know. Please let us know if you encounter any other difficulties with the device.

Thanks,

Scott

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TMAG5170-Q1: TMAG5170 - SDO/SDI idle state