NEC V854 UPD703006 User Manual page 288

(1) Dedicated baud rate generators (BRG0 to BRG3)
The dedicated baud rate generators (BRGn) consist of an 8-bit timer (TMBRGn) that generates a serial clock
for transmission/reception, a compare register (BRGCn), and a prescaler (n = 0 to 3).
(a) Input clock
Internal system clock ( φ ) is input to the BRGn.
(b) Set-up value of BRGn
(i) UART
If the dedicated baud rate generator is specified for UART as a serial clock source, the actual baud
rate can be calculated by the following expression, because a sample rate of x16 is used:
Baud rate =
where,
φ : Internal system clock frequency [Hz]
m: BRGC0 set-up value (1 ≤ m ≤ 256
k : BPR00 to BPR02 prescaler set-up value
Note 256 is set by writing 0 to the BRGC0 register.
(ii) CSI0 to CSI3
If the dedicated baud rate generator is specified for CSIn, the actual baud rate can be calculated
by the following expression (n = 0 to 3):
Baud rate =
where,
φ : Internal system clock frequency [Hz]
m: BRGCn set-up value (1 ≤ m ≤ 256
k : BPRn0 to BPRn2 prescaler set-up value
Notes 1. m = 256 is set by writing 0 to the BRGCn register.
2. Setting k = 0 is prohibited.
Table 8-6 shows the setup values of the baud rate generator when the typical clocks are used.
288
CHAPTER 8 SERIAL INTERFACE FUNCTION
φ
[bps]
m x 2 k x 16 x 2
Note
φ
[bps]
m x 2 k x 2
Note 1
User's Manual U11969EJ3V0UM00
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Note 2