CHAPTER 11 SERIAL INTERFACE FUNCTION
User’s Manual U15109EJ3V0UD
441
11.6.3 Operations
UARTn has the following two operation modes.
•
Operation stopped mode
•
Asynchronous serial interface mode
(1) Operation stopped mode
In this mode, serial transfers are not performed, thus enabling a reduction in power consumption.
In operation stopped mode, pins can be used as ordinary port pins.
(a) Register settings
Operation stopped mode settings are made via bits TXEn and RXEn of asynchronous serial interface mode
register n (ASIMn).
Figure 11-43. ASIMn Setting (Operation Stopped Mode)
After reset:
00H
R/W
Address: ASIM0:
FFFFF300H
ASIM1:
FFFFF310H
ASIM2:
FFFFF230H
ASIM3:
FFFFF2B0H
<7>
<6>
5
4
3
2
1
0
ASIMn
TXEn
RXEn
PS1n
PS0n
UCLn
SLn
ISRMn
0
(n = 0 to 3)
TXEn
RXEn
Operating mode
RXDn/Pxx pin
function
TXDn/Pxx pin
function
0
0
Operation stopped
Port function
Port function
Cautions 1.
Do not switch the operating mode until after the current serial transmit/receive
operation has stopped.
2.
Always set bit 0 to 0.