MLX90129 datasheet(39/60 Pages) MELEXIS

39 / 60 page

MLX90129

13.56MHZ SENSOR TAG / DATALOGGER IC

Page 39 of 60

REVISION 011 - JUNE 13, 2017

3901090129

Interrupt of DMA process

The microcontroller or the RFID base-station can read the DMA status register and access the DMA configuration register to start

and control the DMA processing. At any time, they can hold the DMA process and check the current status of the copied data

(telling how many words have been copied). Then, they can change the DMA configuration to a new one or continue the

processing. While the DMA is processing data or is on hold, any change of the parameters in the DMA configuration words does

not cause the expected changes in the behaviour.

End of DMA process

At the end of the sequence, the MLX90129 may enter its sleep mode or its stand-by mode. During the Sleep mode, the system

may be interrupted by a RFID field, or by the SS line asserted low during 1.5ms.

Command[7:0]

MOSI

SCK

Wake_up =1.5 ms

9.1.3. Setup of the Automatic Logging Mode

Setup

In order to enable the automatic logging mode, the following sequence must be run:

_ Setup the DMA configuration word

_ Setup the DMA source start address, DMA destination start address and the DMA length.

_ If an external EEPROM is used, setup the SPI-master configuration and command word

_ setup the sensor interface configurations in the EEPROM.

_ Setup the Sensor control word and the Sensor thresholds words (if required)

_ Setup the Wake-up Timer configuration word

_ Setup the logging period in the wake-up timer

_ To enable the DMA operation, the bit Processing Control of the DMA configuration register must be reset.

_ Set the bit Automatic Logging enable in the wake-up timer configuration to ’1’.

All these actions can be performed automatically after the system boot: the required configuration can be set in the EEPROM.

Then, after power-on, the system reads this configuration and performs the programmed actions. It is not mandatory to store all

the data from a sensor at each iteration, but only the data fitting the conditions defined in the bits Data logging control of the

Logging several sensors and time-stamp

When more than one sensor is selected as a source of automatic logging, the DMA stores subsequently all the sensor output data

in the selected memory. The stored data has a prefix to identify them:

Bit

15:14

13:0

Definition

Prefix

ADC output code

The prefix code is defined in the following table:

Prefix code

Related sensor or parameter

Sensor 0

Sensor 1

Sensor 2

Iteration index (Time stamp)

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