S6A0074 Datasheet, PDF (43/68 Pages) Samsung semiconductor – 34COM/80SEG DRIVER & CONTROLLER FOR DOT MATRIX LCD

34COM/80SEG DRIVER & CONTROLLER FOR DOT MATRIX LCD
S6A0074
INTERFACE WITH MPU IN SERIAL MODE
When IM port input is "Low", serial interface mode is started. At this time, all three ports, SCLK (synchronizing
transfer clock), SID (serial input data), and SOD (serial output data), are used. If you want to use S6A0074 with
other chips, chip select port (CS) can be used. By setting CS to "Low", S6A0074 can receive SCLK input. If CS is
set to "High", S6A0074 reset the internal transfer counter. Before transfer real data, start byte has to be
transferred. It is composed of succeeding 5 "High" bits, read write control bit (R/W), register selection bit (RS),
and end bit that indicates the end of start byte. Whenever succeeding 5 "High" bits are detected by S6A0074, it
makes serial transfer counter reset and ready to receive next information. The next input data are register
selection bit that determine which register will be used, and read write control bit that determine the direction of
data. Then end bit is transferred, which must have "Low" value to show the end of start byte (Refer to Fig 13. Fig
14).
Write Operation (R/W = 0)
After start byte is transferred from MPU to S6A0074, 8-bit data is transferred which is divided into 2 bytes, each
byte has 4 bit's real data and 4 bit's partition token data. For example, if real data is "10110001" (D0 - D7), then
serially transferred data becomes "1011 0000 0001 0000" where 2nd and 4th 4 bits must be "0000" for safe
transfer. To transfer several bytes continuously without changing RS bit and RW bit, start byte transfer is needed
only at first starting time. Namely, after first start byte is transferred, real data can be transferred succeeding.
Read Operation (R/W = 1)
After start byte is transferred to S6A0074, MPU can receive 8-bit data through the SOD port at a time from the
LSB. Wait time is needed to insert between start byte and data reading, because internal reading from RAM
requires some delay. Continuous data reading is possible like serial write operation. It also needs only one start
bytes, only if you insert some delay between reading operations of each byte. During the reading operation,
S6A0074 observes succeeding 5 "High" from MPU. If it is detected, S6A0074 restarts serial operation at once
and ready to receive RS bit. So in continuous reading operation, SID port must be "0".
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