Table of Contents
Advertisement
to φ/2) selected in bits CKS2 to CKS0 is output continuously from pin SCK
clock is used, pin SCK
Data Transfer Format
Figure 10.2 shows the data transfer format. Data is sent and received starting from the least
significant bit, in LSB-first format. Transmit data is output from one falling edge of the serial
clock until the next falling edge. Receive data is latched at the rising edge of the serial clock.
SCK
1
SO /SI
Bit 0
1
1
Data Transfer Operations
Transmitting: A transmit operation is carried out as follows.
• Set bits SO1 and SCK1 in PMR3 TO 1 so that the respective pins function as SO
necessary, set bit POF1 in port mode register 2 (PMR2) for NMOS open drain output at pin
SO
.
1
• Clear bit SNC1 in SCR1 to 0, and set bit SNC0 to 1 or 0, designating 8- or 16-bit synchronous
transfer mode. Select the serial clock in bits CKS3 to CKS0. Writing data to SCR1 initializes
the internal state of SCI1.
• Write transmit data in SDRL and SDRU, as follows.
⎯ 8-bit transfer mode: SDRL
⎯ 16-bit transfer mode: Upper byte in SDRU, lower byte in SDRL
• Set the SCSR1 start flag (STF) to 1. SCI1 starts operating and outputs transmit data at pin SO
• After data transmission is complete, bit IRRS1 in interrupt request register 1 (IRR1) is set to 1.
When an internal clock is used, a serial clock is output from pin SCK
transmit data. After data transmission is complete, the serial clock is not output until the next time
the start flag is set to 1. During this time, pin SO
transmitted.
When an external clock is used, data is transmitted in synchronization with the serial clock input at
pin SCK
. After data transmission is complete, an overrun occurs if the serial clock continues to be
1
input; no data is transmitted and the SCSR1 overrun error flag (bit ORER) is set to 1.
While transmission is stopped, the output value of pin SO
SCSR1.
is the clock input pin.
1
Bit 1
Bit 2
Bit 3
Figure 10.2 Transfer Format
10. Serial Communication Interface
Bit 4
Bit 5
Bit 6
1
continues to output the value of the last bit
1
can be changed by rewriting bit SOL in
1
Rev.3.00 Jul. 19, 2007 page 257 of 532
. When an external
1
Bit 7
and SCK
1
in synchronization with the
REJ09B0397-0300
. If
1
.
1
Advertisement
Table of Contents
