CHAPTER 14 ASYNCHRONOUS SERIAL INTERFACE (UART)
User’s Manual U16896EJ2V0UD
398
14.3 Registers
(1) Asynchronous serial interface mode register n (ASIMn)
The ASIMn register is an 8-bit register that controls the UARTn transfer operation.
This register can be read or written in 8-bit or 1-bit units.
Reset sets this register to 01H.
Cautions 1. When using UARTn, be sure to set the external pins related to UARTn functions to the
control mode before setting the CKSRn and BRGCn registers, and then set the UARTEn
bit to 1. Then set the other bits.
2. Set the UARTEn and RXEn bits to 1 while a high level is input to the RXDn pin. If these
bits are set to 1 while a low level is input to the RXDn pin, reception will be started.
(1/2)
<7>
UARTEn
ASIMn
(n = 0, 1)
<6>
TXEn
<5>
RXEn
4
PSn1
3
PSn0
2
CLn
1
SLn
0
ISRMn
After reset: 01H R/W Address: ASIM0 FFFFFA00H, ASIM1 FFFFFA10H
UARTEn
Control of operating clock
0
Stop clock supply to UARTn.
1
Supply clock to UARTn.
•
If the UARTEn bit is cleared to 0, UARTn is asynchronously reset
Note
.
•
If the UARTEn bit = 0, UARTn is reset. To operate UARTn, first set the UARTEn bit to 1.
•
If the UARTEn bit is cleared from 1 to 0, all the registers of UARTn are initialized. To set the UARTEn bit to 1
again, be sure to re-set the registers of UARTn.
The output of the TXDn pin goes high when transmission is disabled, regardless of the setting of the UARTEn bit.
TXEn
Transmission enable/disable
0
Disable transmission
1
Enable transmission
•
Set the TXEn bit to 1 after setting the UARTEn bit to 1 at startup. Clear the UARTEn bit to 0 after clearing the
TXEn bit to 0 to stop.
•
To initialize the transmission unit, clear (0) the TXEn bit, and after letting 2 Clock cycles (base clock) elapse, set
(1) the TXEn bit again. If the TXEn bit is not set again, initialization may not be successful. (For details about the
base clock, refer to
14.6.1 (1) Base clock
.)
Note
The ASISn, ASIFn, and RXBn registers are reset.
Содержание V850ES/KE1+
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