AT91SAM7A1-AU Atmel, AT91SAM7A1-AU Datasheet - Page 60

• Manufacturer Part Number: AT91SAM7A1-AU
• Description: IC ARM7 MCU 32BIT ROMLESS144LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7A1-AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 40MHz
• Connectivity: CAN, EBI/EMI, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 49
• Program Memory Type: ROMless
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 144-LQFP
• For Use With: AT91SAM7A1-EK - BOARD EVAL FOR AT91SAM7A1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Program Memory Size: -

11. Clock Manager (CM)
Figure 11-1. Clock Management
60
RTCKO
PLLRC
MCKO
RTCKI
MCKI
AT91SAM7A1
Oscillator
(4 - 16 MHz)
(32.768 kHz)
Oscillator
Real Time
MCKEN
Oscillator
CM_CS.7
RTCKEN
Master
Clock
Clock
The AT91SAM7A1 microcontroller provides:
Clock management is done through the Clock Manager (CM). This allows the user to select
between the different working modes LPM, SLM and OPE.
At power-up, the master clock oscillator and the real-time clock oscillator are enabled. As the
application may or may not use the real-time clock oscillator, the DIVCLK clock is used as the
low-frequency clock (LFCLK). This ensures that both the CORECLK and the LFCLK clock can
be used at power-up.
At power-up, the PLL is disabled (PLLSCLT = 0 in the CM_CS register) to allow the user to
select the application CORECLK frequency.
CM_MDIV
MDIV[6:0]
• 32.768 kHz oscillator (real-time clock oscillator)
• 4 MHz to 16 MHz oscillator
• Programmable PLL (x2 to x20)
• Programmable master clock divider
Programmable
.N
(x2 to x20)
RTCK
PLLEN
PLL
DIVEN
CM_CS.6
RTCSEL
MCK
PLLCLK
DIVCLK
.2
CM_PDIV.15
PLLDIV2
1
0
0
1
CM_CS.2
PLLSLCT
RTCSLCT
1
0
CM_CS.5
DIVSLCT
0
1
LFCLK
CM_CS.3
LFSLCT
0
1
6048B–ATARM–29-Jun-06
CORECLK