LDC1000 INTB pin not showing DRDY

Drew Westrick

I'm developing a driver for the LDC1000 with a freescale KE06 microcontroller. I'd like to use the DRDY pin to trigger an interrupt when it is time to sample the Proximity value. When I set the INTB Config register (0x0A) to the DRDY state (0x04) I don't see the INTB signal changing when I read the proximity register (0x21).

The config registers are set as follows:

0x01 - 0x1D (RpMax)
0x02 - 0x3F (RpMin)
0x03 - 0xCE (Sensor Freq)
0x04 - 0x12 (LDC Config)
0x05 - 0x00 (Clock Config)
0x06 - 0x05 (Cmp High LSB)
0x07 - 0x14 (Cmp High MSB)
0x08 - 0xCE (Cmp Low LSB)
0x09 - 0x12 (Cmp Low MSB)
0x0A - 0x04 (INTB Config)
0x0B - 0x01 (Power Config)

Please Advise

over 10 years ago

0 Natallia Holubeva1 over 10 years ago

TI__Expert 6550 points

Hello Drew,

Could you please explain why are you writing 0x04 to INTB?

Best Regards,

Natallia Holubeva

0 Drew Westrick over 10 years ago in reply to Natallia Holubeva1

Intellectual 880 points

Natallia,

If I'm not mistaken, 100 refers to 0b100 (I'm looking to utilize the DRDY on INTB) and the hex representation would be 0x4. Since the top 5 bits of the byte are reserved to 0 that would make the byte hex 0x04. Correct me if I'm missing something on the datasheet.

Thanks,

Drew

0 Natallia Holubeva1 over 10 years ago in reply to Drew Westrick

TI__Expert 6550 points

Hello Drew,

Your settings look fine to me. Could you please try reading the status and the data in a single CSB read to see if INTB will respond? How long do you wait for data ready? Also, what is the output circuit on INTB? Are you driving it high with a low R pullup?

Best Regards,

Natallia Holubeva

0 Drew Westrick over 10 years ago in reply to Natallia Holubeva1

Intellectual 880 points

Natallia,

I am currently reading the the proximity data (0x21) in a single CSB read. Would you like me to try reading both the proximity data and the status register in a single CSB read? Right now I don't have any pull-up or pull down resistors on the INTB pin. I've tried attaching a weak pull-up (10k) to the INTB pin, but it didn't make a difference. Is the INTB a driven pin or is it an open collector output? I'm also looking for the output to change over the course of a second or two.

Thanks,

Drew

0 Natallia Holubeva1 over 10 years ago in reply to Drew Westrick

TI__Expert 6550 points

Hello Drew,

The INTB is a push-pull. Yes, Could you please read both the proximity data and the status in 1 read?

Best Regards,

Natallia Holubeva

0 Natallia Holubeva1 over 10 years ago in reply to Natallia Holubeva1

TI__Expert 6550 points

Drew,

One more thing: please check if you are changing MOSI at the correct time. We sample “SDI” on the rising edge of “SCLK”.

Best Regards,
Natallia Holubeva

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LDC1000 INTB pin not showing DRDY