MCF51EM256CLL Freescale Semiconductor, MCF51EM256CLL Datasheet - Page 408

• Manufacturer Part Number: MCF51EM256CLL
• Description: IC MCU 32BIT 256KB FLASH 100LQFP
• Manufacturer: Freescale Semiconductor
• Series: MCF51EMr

Specifications of MCF51EM256CLL

• Core Processor: Coldfire V1
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: I²C, SCI, SPI
• Peripherals: LCD, LVD, PWM, WDT
• Number Of I /o: 63
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 16K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 3.6 V
• Data Converters: A/D 16x12b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 100-LQFP
• Processor Series: MCF51EM
• Core: ColdFire V1
• Data Bus Width: 32 bit
• Data Ram Size: 16 KB
• Interface Type: RS-232, LIN
• Maximum Clock Frequency: 50 MHz
• Number Of Timers: 3
• Operating Supply Voltage: 1.8 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JLINK-CF-BDM26, EWCF
• Development Tools By Supplier: DEMOEM
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

COUNTDOWN_COUNT
Independent Robust Real Time Clock (IRTC)
17.5.13 IRTC Countdown (Minutes) Timer Register (IRTC_COUNT_DN)
This counter is used to generate an interrupt on a minute boundary, for example, to turn off the LCD
controller after five minutes of inactivity. The countdown timer is decremented by the minute (MIN) tick
output from the real-time clock, so the average tolerance of the count is 0.5 minutes. For better accuracy,
enable the countdown timer by waiting for the MIN bit of the IRTC_ISR register to be set (i.e. waiting for
the minute interrupt). Loading the countdown timer counter with 0 will have no effect. Software reset
brings the countdown timer count to its default state. Interrupt is generated when the timer reaches 0. The
value in the register shows the current value of the counter at all times. Note that the actual delay includes
the seconds from setting the countdown to the next minute tick.
The max value is 99 as in BCD mode, a value bigger than 99 cannot be displayed in 8-bits. Programming
a value bigger than 99 does not ensure correct reading in BCD mode. However binary value can still be
read.
17-24
Reset Value
Reset Value
IRTC_COUNT_DN
Field (bcd)
Field (bcd)
Field
15–8
Field (bin)
Field (bin)
7–0
Bit Type
Bit Type
Figure 17-14. IRTC Countdown (Minutes) Timer Register (IRTC_COUNT_DN)
MCF51EM256 Series ColdFire Integrated Microcontroller Reference Manual, Rev. 8
Bit 15
rsvd
Bit 7
rw
—
0
Reserved Bits. Read returns zeros.
Countdown counter value. Valid count values: 1 – 99.
COUNTDOWN_COUNT (tens)
Table 17-16. IRTC_COUNT_DN Field Descriptions
Bit 14
rsvd
Bit 6
—
rw
0
Bit 13
rsvd
Bit 5
rw
—
0
Countdown (Minutes) Timer Register
COUNTDOWN_COUNT
Bit 12
rsvd
Bit 4
rw
—
0
Bit 11
rsvd
Description
Bit 3
—
rw
0
COUNTDOWN _COUNT (units)
Bit 10
rsvd
Bit 2
rw
—
0
rsvd
Bit 9
Bit 1
rw
—
0
Freescale Semiconductor
rsvd
Bit 8
Bit 0
Offset: 0x18
rw
—
0
0x18
0x19