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CHAPTER 13 UART
MB90560 series
13.5 UART Interrupts
UART uses both reception and transmission interrupts. An interrupt request can be
generated for either of the following causes:
Receive data is transferred to the serial input register (SIDR0/1), or a reception
error occurs.
Transmission data is transferred from the serial output data register 1
(SODR0/1) to the transmission shift register.
The extended intelligent I-O service (EI2OS) is available for these interrupts.
I
UART Interrupts
Table 13.5-1 lists the interrupt control bits and causes of UART.
Table 13.5-1
Interrupt control bits and interrupt causes of UART
o : Used
x
: Not used
G
Reception Interrupt
register is set to “1”:
Data reception is complete (SSR0/1: RDRF)
Overrun error (SSR0/1: ORE)
Framing error (SSR0/1; FRE)
Parity error (SSR0/1: PE)
When at least one of the flag bits is “1” and the reception interrupts are enabled (SSR0/1:
RIE=1), a reception interrupt request is generated to the interrupt controller.
When the serial input data register (SIDR0/1) is read, the receive data full flag (SSR0/1: RDRF)
is automatically cleared to “0”. When “0” is written to the REC bit of the serial control register
(SCR0/1), all the reception error flags (SSR0/1: PE, ORE, and FRE) are cleared to “0”.
Reception/
transmission
Interrupt
request flag bit
Operation mode
Interrupt cause
Interrupt cause
enable bit
When interrupt
request flag is
cleared
0
1
2
Reception
RDRF
o
o
o
Loading receive
data into buffers
(SIDR0/1)
SSR0/1:RIE
Receive data is
read.
ORE
o
o
o
Overrun error
0 is written to
the reception
error flag clear
bit (SSR1: REC).
FRE
o
o
x
Framing error
PE
o
x
x
Parity error
Transmission
TDRE
o
o
o
Empty transmission
buffer (SODR0/1)
SSR0/1:TIE
Transmission data
is written.