AS1122
Datasheet ꢀ Detailed Description
8 Detailed Description
Serial Interface
The AS1122 features a 4ꢀpin (CLKI, CLKO, SDI, and SDO) serial interface, which can be connected to microcontrollers or digital signal procesꢀ
sors.
The rising edge of the CLKI signal shifts data from pin SDI to the internal register. After all data are clocked in, the serial data are latched into the
internal registers at the rising edge of the internal LD signal (see Figure 24). The internal LD signal is triggered after the clk is low for a time tCAPT
and all Data are clocked in.
With the first 8 clkꢀcycles an 8 bit identifier needs to be send to the device to distinguish between Status Information, Dot Correction, PWM or
command data.
After the internal LD signal the internal counter is set to 0 again and the data are latched into the register according to the prior identifier. If the LD
triggers and the counter has no valid value (80 bit for DotꢀCorrection, 152 bit for PWM data or 16 bit for command data), the counter is set to 0
but the data will be ignored.
With the falling edge of the CLKO the data is shifted to SDO.
Figure 24. PWM Cycle Timing Diagram
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