CMT2380F17
Rev0.1 | 201/347
www.cmostek.com
In addition to the standard operation, the UART0 can perform framing error detection by looking for
missing stop bits, and automatic address recognition.
。
18.1
Serial Port 0 Mode 0
Serial data enters and exits through RXD0. TXD0 outputs the shift clock. 8 bits are transmitted/received:
8 data bits (LSB first). The shift clock source can be selected to 1/12 or 1/4 the system clock frequency by
URM0X3 setting in S0CFG register.
Figure 18
–3 shows a simplified functional diagram of the serial port 0 in Mode 0.
Transmission is initiated by any instruction that uses S0BUF as a destination register. The “write to
S0BUF” signal triggers the UART0 engine to start the transmission. The data in the S0BUF would be shifted
into the RXD0(P3.0) pin by each raising edge shift clock on the TXD0(P3.1) pin. After eight raising edge of
shift clocks passing, TI0 would be asserted by hardware to indicate the end of transmission and its interrupt
vector can be switched to System Flag interrupt by BTI and UTIE gated. Figure 18
–4 shows the transmission
waveform in Mode 0.
Reception is initiated by the condition REN0=1 and RI0=0. At the next instruction cycle, the Serial Port 0
Controller writes the bits 11111110 to the receive shift register, and in the next clock phase activates Receive.
Receive enables Shift Clock which directly comes from RX Clock to the alternate output function of TXD0
pin. When Receive is active, the contents on the RXD0 pin would be sampled and shifted into shift register by
falling edge of shift clock. After eight falling edge of shift clock, RI0 would be asserted by hardware to indicate
the end of reception. Figure 18
–5 shows the reception waveform in Mode 0.
UART engine
80C51 Internal BUS
TXBUF
RXBUF
80C51 Internal BUS
REN0
RI0
Read
S0BUF
Write
S0BUF
URM0X3
TX Clock
RX Clock
SYSCLK
“
0
”
“
1
”
TI0
RI0
Serial Port 0 Interrupt
Shift-clock
RXD0 Alternated
for Input/output
Function
TXD0 Alternated
for output
Function
RXSTART
4
12
BTI
System Flag Interrupt
UTIE
ESF
Figure 18-3. Serial Port 0 Mode 0
Содержание CMT2380F17
Страница 27: ...CMT2380F17 Rev0 1 27 347 www cmostek com 1 25 Phase Noise...
Страница 111: ...CMT2380F17 Rev0 1 111 347 www cmostek com INT2IS 1 0 Selected Port Pin of nINT2 00 P4 4 01 P3 0 10 P1 1 11 P1 6...
Страница 131: ...CMT2380F17 Rev0 1 131 347 www cmostek com Figure 16 1 Timer 0 Mode 0 Structure Figure15 2 Timer 1 Mode 0 Structure...
Страница 161: ...CMT2380F17 Rev0 1 161 347 www cmostek com Figure 16 32 Split Timer 3 Mode 1 Structure AR with Ex INT...
Страница 177: ...CMT2380F17 Rev0 1 177 347 www cmostek com Figure 17 3 PCA Interrupt System...
Страница 239: ...CMT2380F17 Rev0 1 239 347 www cmostek com Figure 19 5 8 bit Timer Mode Configuration for S1BRG S1TME 1...
Страница 246: ...CMT2380F17 Rev0 1 246 347 www cmostek com SnMIPS S0MI S1MI 1 P3 3 P4 7...
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