MCF5307CFT66B Freescale Semiconductor, MCF5307CFT66B Datasheet - Page 303

• Manufacturer Part Number: MCF5307CFT66B
• Description: IC MPU 32BIT 66MHZ COLDF 208FQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF530xr

Specifications of MCF5307CFT66B

• Core Processor: Coldfire V3
• Core Size: 32-Bit
• Speed: 66MHz
• Connectivity: EBI/EMI, I²C, UART/USART
• Peripherals: DMA, POR, WDT
• Number Of I /o: 16
• Program Memory Type: ROMless
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 208-FQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Program Memory Size: -
• Data Converters: -

T0_LOOP
T0_FINISH
13.5 Calculating Time-Out Values
The formula below determines time-out periods for various reference values:
When calculating time-out periods, add 1 to the prescaler to simplify calculating, because
TMRn[PS] = 0x00 yields a prescaler of 1 and TMRn[PS] = 0xFF yields a prescaler of 256.
For example, if a 45-MHz timer clock is divided by 16, TMRn[PS] = 0x7F, and the timer
is referenced at 0xABCD (43,981 decimal), the time-out period is as follows:
The time-out values in Table 13-5 represent the time it takes the counter value in TCNn
value to go from 0x0000 to the default reference value, TRRn[REF] = 0xFFFF. Time-out
values shown for BCLKO are divided by 1 and by 16 (TMRn[CLK] is 01 or 10,
respectively).
Any clock source (BCLKO ÷ 1, BCLKO ÷ 16, or TIN) can be prescaled using TMRn[PS].
The BCLKO frequency depends on the prescaler value (TMRn[PS]) and on the PLL clock
setting, as described inChapter 7, “Phase-Locked Loop (PLL).”
Decimal
TMR[PS]
0
1
2
3
4
5
move.w TMR0,D0;save the contents of TMR0 while setting
bset #0,D0 ;the 0 bit. This enables timer 0 and starts counting
move.w D0, TMR0 ;load the value back into the register, setting TMR0[RST]
move.b TER0,D1 ;load TER0 and see if
btst #1,D1 ;TER0[REF] has been set
beq T0_LOOP
addi.l #1,D2;Increment D2
cmp.l #5,D2;Did D2 reach 5? (i.e. timer ref has timed)
beq T0_FINISH;If so, end timer0 example. Otherwise jump back.
move.b #0x02,D0 ;writing one to TER0[REF] clears the event flag
move.b D0,TER0
jmp T0_LOOP
HALT;End processing. Example is finished
Time-out period = (1/clock frequency) x (1 or 16) x (TMRn[PS] + 1) x
(TRRn[REF])
Time-out period = (1/45) x (16) x (127 + 1) x (43,981) = 1.67 S
Table 13-5. Calculated Time-out Values (90-MHz Processor Clock)
Hex
0
1
2
3
4
5
0.06991
0.09321
0.11651
0.13981
TMR[CLK] = 10 (System Bus Clock/16)
45 MHz
0.0233
0.0466
Freescale Semiconductor, Inc.
For More Information On This Product,
0.03495
0.06991
0.10486
0.13981
0.17476
0.20972
30 MHz
Chapter 13. Timer Module
Go to: www.freescale.com
22.5 MHz
0.09321
0.13981
0.18641
0.23302
0.27962
0.0466
0.00146
0.00291
0.00437
0.00583
0.00728
0.00874
45 MHz
TMR[CLK] = 01 (System Bus Clock/1)
Calculating Time-Out Values
0.00218
0.00437
0.00655
0.00874
0.01092
0.01311
30 MHz
22.5 MHz
0.00291
0.00583
0.00874
0.01165
0.01456
0.01748
13-7