Rainbow-electronics AT89C51SND1C Manual do Utilizador descarregar pdf (Página 139)

139

AT8xC51SND1C

4109E–8051–06/03

Notes: 1. These frequencies are achieved in X1 mode, F

PER

= F

OSC

÷ 2.

2. These frequencies are achieved in X2 mode, F

PER

= F

OSC

Baud Rate Selection (Mode 2) In mode 2, the baud rate can only be programmed to 2 fixed values: 1/16 or 1/32 of the

peripheral clock frequency.

As shown in Figure 107 the selection is done using SMOD1 bit in PCON register.

Figure 108 gives the baud rate calculation formula depending on the selection.

Figure 107. Baud Rate Generator Selection (Mode 2)

Table 124. Internal Baud Rate Generator Value

Baud Rate

PER

= 6 MHz

(1)

PER

= 8 MHz

(1)

PER

= 10 MHz

(1)

SPD SMOD1 BRL Error % SPD SMOD1 BRL Error % SPD SMOD1 BRL Error %

115200 - -----------

57600 - - - - 1 1 247 3.55 1 1 245 1.36

38400 1 1 246 2.34 1 1 243 0.16 1 1 240 1.73

19200 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36

9600 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16

4800 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16

Baud Rate

PER

= 12 MHz

(2)

PER

= 16 MHz

(2)

PER

= 20 MHz

(2)

SPD SMOD1 BRL Error % SPD SMOD1 BRL Error % SPD SMOD1 BRL Error %

115200 - - - - 1 1 247 3.55 1 1 245 1.36

57600 1 1 243 0.16 1 1 239 2.12 1 1 234 1.36

38400 1 1 236 2.34 1 1 230 0.16 1 1 223 1.36

19200 1 1 217 0.16 1 1 204 0.16 1 1 191 0.16

9600 1 1 178 0.16 1 1 152 0.16 1 1 126 0.16

4800 1 1 100 0.16 1 1 48 0.16 1 0 126 0.16

SMOD1

PCON.7

PER

CLOCK

÷ 2

÷ 16

To Serial Port

1 2 ... 134 135 136 137 138 139 140 141 142 143 144 ... 209 210

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