DVK90129 Melexis Inc, DVK90129 Datasheet - Page 33

• Manufacturer Part Number: DVK90129
• Description: DEVELOPMENT KIT MLX90129
• Manufacturer: Melexis Inc
• Series: -r
• Type: Development kitr

Specifications of DVK90129

• Contents: Board, Proxima RF™ Desktop Reader
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: MLX90129

9 Device Configuration
9.1.1 Main features
The Datalogger application is managed by the DMA (Direct Memory Access) unit. This block controls the
standalone applications, without any external microcontroller. It handles the start-up operations, and sends
the data from a programmed source towards a programmed destination, using flexible protocol and interrupt
conditions. Typically, it may get the data from the sensor interface and store it in an EEPROM. It works on
defined time periods controlled by a wake-up timer.
Its main features are the following:
9.1.2 DMA operations
Loading of the register file from the EEPROM data.
At the power-up of the battery, the DMA automatically loads the Register File with its image from the
EEPROM. A bit stored in the EE-Latch bank, called Disable Automatic Loading, can be set to disable this
automatic loading.
At any time, the RFID or the SPI interface can send an Update command to update the content of the
Register File with the values stored in the EEPROM.
The configuration may be chosen in such a way that DMA operations start automatically at power-up.
Data logging in the internal or external EEPROM
After power-up, the DMA loads the Register File with the data stored in the EEPROM (it also loads its own
configuration).
The wake-up timer (WUT) starts counting to a programmed value. During this counting, the MLX90129 works
in a sleep mode, consuming a very low power. To save power, the duty cycle should be as low as possible.
At the end of the counting, the WUT wakes the DMA up.
The DMA loads the configuration registers of the selected sensor, and starts a sensor acquisition.
The result data is then stored in the EEPROM, at an address calculated from a programmed value.
Depending on the options, the DMA may configure and start an acquisition of another sensor, or may let the
system enter the sleep mode. If another sensor is selected, then the DMA loads the new sensor configuration
before starting the acquisition.
At any moment, this process may be interrupted by an external microcontroller, to read the data collection.
For that, it asserts low the bit Processing Control of the DMA configuration
be hold or reset. In order to store only the latest data from ADC, the bit Loop enable must be set. In this case,
the old data is rewritten by the DMA unit with the new one when the memory border has been reached. When
the memory is completely filled, a Full Memory interrupt appears on the pad IRQ. It is also possible to send
3901090129
Rev 007
9.1 Standalone datalogger
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The configuration registers are filled from the EEPROM at the start-up (when enabled)
The duty-cycle (ratio between active and sleep mode) is controlled by a wake-up timer (WUT) that
wakes the system up after a programmed delay
Programmed behaviour (source, destination, interrupt options, master-SPI options, …)
Programmable command-set to address any kind of external SPI memory
Programmable timings used in the SPI protocol of the external memory (between the request and the
response)
Calculation of the address of the destination.
13.56MHZ SENSOR TAG / DATALOGGER IC
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register.
MLX90129
Then, the process may
Data Sheet
March 2011