13 SeRial inTeRFaCe
13-6
Seiko epson Corporation
S1C63003/004/008/016 TeChniCal Manual
(Rev. 1.1)
Serial Data input/Output Permutation
13.6.3
The S1C63004/008/016 allows the input/output permutation of serial data to be selected by the SDP register as to
either LSB first or MSB first. The block diagram showing input/output permutation in case of LSB first and MSB
first is provided in Figure 13.6.3.1. The SDP register should be set before setting data to SD[7:0].
SIN
SIN
Address [FF5CH]
Address [FF5BH]
Address [FF5CH]
Address [FF5BH]
Output
latch
Output
latch
SOUT
SOUT
SD3 SD2 SD1 SD0
SD4 SD5 SD6 SD7
SD7 SD6 SD5 SD4
SD0 SD1 SD2 SD3
(LSB first)
(MSB first)
6.3.1 Serial data input/output permutation
Figure 13.
SRDY Signal
13.6.4
When the S1C63004/008/016 serial interface is used in the slave mode, the SRDY signal is used to indicate whether
the internal serial interface is ready to transmit or receive data for the master side (external) serial device. The SRDY
signal is output from the SRDY (P33) terminal. When using the SRDY output in slave mode, write "1" to the ENCS
and ESREADY registers (this signal cannot be used in SPI slave mode).
Output timing of SRDY signal is as follows:
• When positive polarity (SCPS1 = "0") is selected for the synchronous clock:
The SRDY signal goes "1" (high) when the S1C63004/008/016 serial interface is ready to transmit or receive
data; normally, it is at "0" (low).
The SRDY signal changes from "0" to "1" immediately after "1" is written to SCTRG and returns from "1" to "0"
when "1" is input to the SCLK (P30) terminal (i.e., when the serial input/output begins transmitting or receiving
data). Moreover, when high-order data is read from or written to SD[7:4], the SRDY signal returns to "0."
• When negative polarity (SCPS1 = "1") is selected for the synchronous clock:
The SRDY signal goes "0" (low) when the S1C63004/008/016 serial interface is ready to transmit or receive data;
normally, it is at "1" (high).
The SRDY signal changes from "1" to "0" immediately after "1" is written to SCTRG and returns from "0" to "1"
when "0" is input to the SCLK (P30) terminal (i.e., when the serial input/output begins transmitting or receiving
data). Moreover, when high-order data is read from or written to SD[7:4], the SRDY signal returns to "1."
Timing Chart
13.6.5
The S1C63004/008/016 serial interface timing charts are shown in Figure 13.6.5.1.