AT89C51IC2_14 Datasheet, PDF (51/147 Pages) ATMEL Corporation – During UART Reception, Clearing REN may Generate Unexpected IT

AT89C51IC2
Internal Baud Rate Generator
(BRG)
When the internal Baud Rate Generator is used, the Baud Rates are determined by the
BRG overflow depending on the BRL reload value, the value of SPD bit (Speed Mode)
in BDRCON register and the value of the SMOD1 bit in PCON register.
Figure 21. Internal Baud Rate
Peripheral clock
BRR
auto reload counter _overflow
/2
/6
0
BRG
1
BRL
SPD
0
INT_BRG
1
• The baud rate for UART is token by formula:
BaudRate
=
-------------------------²----^S--^M-----^O----^D-----^×----^F----^C----^L---^K---^P----^E---^R---^I--^P----^H--------------------------
2 × 2 × 6 〈 1 – SPD〉 × 16 × [256 – (BRL)]
(BRL)
=
256
–
---------------²----^S--^M-----^O----^D---¹-----^×----^F----^C----^L---^K----^P---^E---^R---^I--^P----^H----------------
2 × 2 × 6_{(1 – SPD)} × 16 × BaudRate
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4301D–8051–02/08