6.4.4 Baud-Clock Generator
The baud-clock generator is basically a phase accumulator that produces a baud clock as the result of phase overflow from the most
significant bit of the phase shift circuitry. As illustrated in Figure 6-7, a user-programmable 16-bit phase register (PR0) is used to select
a suitable phase value for its baud clock. The phase value dictates the phase period of the accumulation process. The phase value
(from PR0) is added to the current phase accumulator value on each system clock (SMOD = 1) or every 4th system clock (SMOD =
0). The baud clock is the result of the addition overflow out of the most significant bit of the phase accumulator (bit 16). The baud-clock
generator output is always divided by 16 to produce the exact baud rate.
The following two formulas can be used to calculate the output of the baud-clock generator and the resultant mode 1, 3 baud rates.
Additionally, Table 6-4 gives example phase register (PR0) settings needed to produce some more common baud rates at certain sys-
tem clock frequencies (assuming SMOD = 1).
Baud-Clock Generator Output (BAUD) = System Clock Frequency x PR0 / 2
17
Baud Rate for Modes 1 and 3 = BAUD x 2
(SMOD x 2)
/ 2
6
Table 6-4. Example Baud-Clock Generator Settings (SMOD = 1)
Figure 6-7. UART Baud-Clock Generator
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