How to read and write to registers of MMA7660 using TWI

RE: How to read and write to registers of MMA7660 using TWI

bjorn-spockeli — Mon, 03 Apr 2017 14:05:34 GMT

In order to enable Tap detection in the device the user must enable the Tap Interrupt in the INTSU (0x06) register and AMSR [2:0] = 000 in the SR (0x08) register. In this mode, TILT (0x03) register, XOUT (0x00), YOUT (0x01), and ZOUT (0x02) registers will update at the 120 samples/second. The user can configure Tap Detection to be detected on X and/or Y and/or Z axes. The customer can configure this by changing the XDA, YDA, and/or ZDA bit in the PDET (0x09) register. Detection for enabled axes is decided on an OR basis: If the PDINT bit is set in the INTSU (0x06) register, the device reports the first axis for which it detects a tap by the Tap bit in the TILT (0x03) register. When the Tap bit in the TILT (0x03) register is set, tap detection ceases, but the device will continue to process orientation detection data. Tap detection will resume when the TILT (0x03) register is read.

RE: How to read and write to registers of MMA7660 using TWI

saiteja — Wed, 15 Mar 2017 05:14:01 GMT

Hi Thank you for reply, i am using TWI_Sensor example code to get Accelerometer(MMA7660) data it is giving XYZ and shake info. here what can be the sample rate i need to use to get TAP. here i am using NRF_TWI_FREQ_400K.

the first thing is i am unable to read and write on registers in accelerometer(that i already mentioned). once againg thank you very much for responding.

RE: How to read and write to registers of MMA7660 using TWI

dav lion — Tue, 14 Mar 2017 14:21:27 GMT

I'm using the MMA7660 in a production board, and gave up trying to get Tap to work. Shake works great, both sampled and as an interrupt source. XYZ values read perfectly. The spec-sheet for the chip notes that Tap is only available when sampling rate is set very high (== higher battery consumption), so you might try that, though I did, without success.

RE: How to read and write to registers of MMA7660 using TWI

saiteja — Thu, 09 Mar 2017 09:19:57 GMT

yes i tried it. it is giving NRF_SUCCESS return value. but i am unable to read the register value.

RE: How to read and write to registers of MMA7660 using TWI

Alex — Thu, 09 Mar 2017 08:04:21 GMT

Did you try to follow this note "NOTE: To write to the registers the MODE bit in the MODE (0x07) register must be set to 0, placing the device in Standby Mode. "?

RE: How to read and write to registers of MMA7660 using TWI

Alex — Wed, 08 Mar 2017 13:03:41 GMT

I'm not familiar with MMA74660 but after writing to any register how do you know if it was changed or not if before printf you don't read register back from MMA74660? Also looking at datasheet found "NOTE: To write to the registers the MODE bit in the MODE (0x07) register must be set to 0, placing the device in Standby Mode. ".