1.3.2. Data Controller
When the data controller receives the signal from the timer indicating that the device does not have any activity for a pre-defined duration, the controller automatically reads the data from the counter and writes the data into the UFM. Upon completion of the task, the data controller then asserts the Power-Down-Ready signal high for the external circuitry to power down the device.
When the device powers up, the data controller automatically goes to the location in the UFM where the data from the counter is stored, and reads back the data before the device powers down again. The controller then reloads the registers of the counter with the data.
The data controller interfaces with the module that instantiates the UFM through the Altera proprietary interface protocol. The controller writes the data to a blank location in the UFM every time before the device is powered down, and reads back the data from the correct location when the device is powered back up.
The controller uses almost all the addresses in sector 0 of the UFM for data storing purposes. The erase operation takes additional time to complete, so when the UFM sector is full, the controller automatically erases that sector.
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