LDC1612: LDC1612 no interrupt happen

Hi,

The INTB pin can be configured in to display various errors, shown on page 25 of the datasheet. It sounds like you are trying to use INTB in its data-ready functionality. In this mode, the INTB pin will assert (drive a logic low) when new data is ready. It will not de-assert until the I2C read command registers. When you read the data does the INTB pin stay low? 

Regards,

Hi,Kristin Jones93!

After I initialize, the pin of INTB is pulled down. When I use metal to get close to the coil, INTB cannot trigger the interruption. So, I want to read the data of channel 0 repeatedly, and I want to use metal objects to get close to the coil, and the data is always the same.

As you said, maybe new data is ready, I can read the data and INTB will pull up, but it is not and at a low logic always .

In addition, about ldc1612 register configuration, only use channel 0, whether channel 1 must be grounded, otherwise it will cause the failure to start;

and Finally, if I need to use the ldc1612 INTB pin  function , when new data is ready, the INTB is pull down, I must read the data register?the INTB will not pull up?

best regards!

Hi,

The INTB pin is likely pulled down after initialization because the device has already completed its first conversion. The INTB pin does not assert when the inductance reduces due to a target present; it asserts whenever the LDC1612 completes a new data conversion. The goal of the INTB pin is to signal the MCU when to initiate an I2C read, not to signal the MCU when a target is present. This is why the INTB pin only de-asserts when the LDC1612 internally registers the I2C read command from the MCU.

It is fine to leave unused channels (INxA and INxB) floating, they do not need to be grounded.

When you read the data register does the INTB pin de-assert (which is a logic high)?

Regards,

Hi,
I get the idea,as you said, the goal of INTB pin is signal MCU when to initiate an i2c read, not to signal the mcu when a target is persent; but i read the data register directly and the INTB pin not de-assert; only when I read the status register and then read the data register will the INTB set high levels;
Will there is no interrupt if the status register not be read?
Best regards!

Hi,

When you read the status register, what is the value? Could you also share how you have configured register 0x19, ERROR_CONFIG? If the INTB pin is asserting due to new data being read, you should not have to read the status register to make INTB de-assert. It should de-assert when you read the DATAx_MSB registers. The fact that reading the status register is de-asserting INTB makes me think that it is acting as an error flag, not a data-ready flag.

Regards,

Hi,Kristin Jones93!

thanks your reply,I'm sorry for not replying  to you in time and apologize!  now I  will give you my register configuration,

CLOCK_DIVIDERS0  0x1002

OFFSET0,                  0x0000

SETTLECOUNT0,      0x000C

RCOUNT0,                 0x04D4

DRIVE_CURRENT0   0x9000

ERROR_CONFIG       0x0001

MUX_CONFIG,           0X020C

CONFIG                      0x1E01

as I said, I have to read the status register and can trigger an interrupt;

on the other hand,  I can read the data by polling read and finish my demand, but I hope can trigger interrupt not read status register first;  

 Best Regards!

Hi,

Thanks for sharing your register values. You have the ERROR_CONFIG register set up correctly, so INTB should only assert when new data is ready. Could you share the value of the STATUS register when you read it and cause INTB to de-assert? And when you read the data registers, are the values changing?

Also, are you using the LDC1612EVM or your own board?

Regards,

Hi,

first: When I set up that's register, then new data is ready ,this is correct. and now only after read status register ,I can read the content of read register.

second : when I read the status register and INTB will assert with the value of STATUS register is 0x00; if I read the STATUS register, the value of DATA register is do changing, At present , all design is on LDC1612EVM board.

on the other hand, I want to ask you a question about the content of data register: if the mental object is in a regular fixed position to coil, the content of data register will not change much, and always change in a small range. Because I want to use this feature implementation the detection mental and coil fixed position's data, other position data I can ignored;

in addition, I open the INTB function and if the INTB is asserted, the interrupt always occurred, and now i can read the data register by directly to read by i2c ,not in a interrupt.

Hi,

Are you using the Sensing Solutions GUI with the LDC1612EVM? Or have you written your own firmware? Based on the register values you've shared, I'm not yet sure why you're having this issue.

As for your other question, yes, if the metal target is held in a fixed position in relation to the coil, the contents of the data registers should not change much.

Regards,