Rainbow-electronics AT89C5132 Manual de usuario descargar pdf (Pagina 115)

115

AT8xC5132

4173A–8051–08/02

Interrupt The Serial I/O Port handles two interrupt sources that are the “end of reception” (RI in

SCON) and “end of transmission” (TI in SCON) flags. As shown in Figure 91 these flags

are combined together to appear as a single interrupt source for the C51 core. Flags

must be cleared by software when executing the serial interrupt service routine.

The serial interrupt is enabled by setting ES bit in IEN0 register. This assumes interrupts

are globally enabled by setting EA bit in IEN0 register.

Depending on the selected mode and wether the framing error detection is enabled or

not, RI flag is set during the stop bit or during the ninth bit as detailed in Figure 92.

Figure 91. Serial I/O Interrupt System

Figure 92. Interrupt Waveforms

IEN0.4

Serial I/O

Interrupt Request

SCON.1

SCON.0

RXD D0D1D2D3D4D5D6D7

Start bit 8-bit data Stop bit

SMOD0 = X

SMOD0 = 1

a. Mode 1

b. Mode 2 and 3

RXD D0D1D2D3D4D5D6 D8

Start bit 9-bit data Stop bit

SMOD0 = 1

SMOD0 = 0

1 2 ... 110 111 112 113 114 115 116 117 118 119 120 ... 161 162

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Rainbow-electronics AT89C5132 Manual de usuario Pagina 115