MC9S08EL32 Datasheet, PDF (223/356 Pages) Freescale Semiconductor, Inc – 8-Bit HCS08 Central Processor Unit (CPU)

Desired Bit Rate:
57,600 bps
External Crystal Frequency: 4.9152 MHz
1 Second
17.36111 μs
=
57,600 Bits
1 Bit
1 Second
2 Clock Out Period
406.901 ns
X
=
4,915,200 Clock Out Period
1 SLIC Clock Period
1 SLIC Clock Period
17.36111 μs
1 SLIC Clock Period
42.67 SLIC Clock Periods
X
=
1 Bit
406.901 ns
1 Bit
Therefore, the closest SLCBT value would be 43 SLIC clocks (SLCBT = 0x002B).
Because you can only use even values in SLCBT, the closest acceptable value is 42 (0x002A).
Figure 12-17. SLCBT Value Calculation Example 1
Desired Bit Rate:
57,600 bps
External Crystal Frequency: 9.8304 MHz
1 Second
17.36111 μs
=
57,600 Bits
1 Bit
1 Second
2 Clock Out Period
203.45 ns
X
=
9,830,400 Clock Out Periods
1 SLIC Clock Period
1 SLIC Clock Period
17.36111 μs
1 SLIC Clock Period
85.33 SLIC Clock Periods
X
=
1 Bit
203.45 ns
1 Bit
Therefore, the closest SLCBT value would be 85 SLIC clocks (SLCBT = 0x0055).
Because you can only use even values in SLCBT, the closest acceptable value is 86 (0x0056)
Figure 12-18. SLCBT Value Calculation Example 2
Desired Bit Rate:
15,625 bps
External Crystal Frequency: 8.000 MHz
1 Second
64 μs
=
15,625 Bits
1 Bit
1 Second
2 Clock Out Period
250 ns
X
=
8,000,000 Clock Out Periods
1 SLIC Clock Period
1 SLIC Clock Period
64 μs
1 SLIC Clock Period
256 SLIC Clock Periods
X
=
1 Bit
250 ns
1 Bit
Therefore, the closest SLCBT value would be 256 SLIC clocks (SLCBT = 0x0100).
Figure 12-19. SLCBT Value Calculation Example 3
MC9S08EL32 Series and MC9S08SL16 Series Data Sheet, Rev. 3
Freescale Semiconductor
225