PRELIMINARY
SF104-P01
SF3013M Fingerprint Image Sensor Module User Manual
Page - 24
The finger detection mode is enabled by setting the EN_DET bit (bit 5 of REG10) to 1.
Finger detect interrupt is enabled by setting the EN_INTR bit (bit 6 of REG11) to 1. Enabling
interrupt also changes the hardware Reset pin to INTR output pin.
In finger detection mode, the hardware logic will periodically scan the row which assign
by REG_INSCANLINE of the pixel array. In instead of sending pixel data to FIFO, the pixel
data bytes are summed up and compared with a threshold value (determined by the
REG_DETH/REG8) at the end of line. If the sum is greater than the content of REG8, then
the interrupt flag will be raised.
Once the “Detect result is OK” status bit or “finger detected” interrupt flag is raised, the
internal image channel will be opened to allow full image data to be transferred to MCU.
The timing period of detection scan is given by:
sysclk_freq / (4096 * (REG9+1))
If at the end of detect scan, the summed pixel is less than the threshold value, the
interrupt flag will be set to (or return to) 0, and also the image data channel will be closed.
Whenever the detection mode control bit is turned on or off, it is required to write (any
value) to the REG_CHMD (REG16) register to inform the internal logic to change the scan
geometry.
There are two status bits in the status register associated with detection mode:
Status.bit5 is the detection interrupt flag, which is set at the end of each detection scan,
and cleared whenever a new scan (either image scan or detection scan) is started.
Status.bit6 is the detection OK flag, which is only set or cleared at the end of a detection
scan. This bit is used to enable or disable the image channel.
Both bit5 and bit6 are cleared by reset.
4.4 Timing considerations
