AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 188
AT91SAM7S256D-AU
Manufacturer Part Number
AT91SAM7S256D-AU
Description
ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
Manufacturer
Atmel
Series
SAM7S256r
Datasheet
1.AT91SAM7S256D-AU.pdf
(775 pages)
Specifications of AT91SAM7S256D-AU
Rohs
yes
Core
ARM
Processor Series
AT91SAM
Data Bus Width
16 bit/32 bit
Maximum Clock Frequency
55 MHz
Program Memory Size
256 KB
Data Ram Size
64 KB
On-chip Adc
Yes
Operating Supply Voltage
3 V to 3.6 V
Operating Temperature Range
- 40 C to + 85 C
Package / Case
LQFP-64
Mounting Style
SMD/SMT
Interface Type
2-Wire, I2S, SPI, USART
Length
7 mm
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
AT91SAM7S256D-AU
Manufacturer:
ATMEL
Quantity:
101
- Current page: 188 of 775
- Download datasheet (5Mb)
24.3.2
24.3.3
24.3.4
Figure 24-2. Typical Crystal Connection
The startup time of the Main Oscillator is given in the DC Characteristics section of the product datasheet. The
startup time depends on the crystal frequency and decreases when the frequency rises.
To minimize the power required to start up the system, the main oscillator is disabled after reset and slow clock is
selected.
The software enables or disables the main oscillator so as to reduce power consumption by clearing the MOSCEN
bit in the Main Oscillator Register (CKGR_MOR).
When disabling the main oscillator by clearing the MOSCEN bit in CKGR_MOR, the MOSCS bit in PMC_SR is
automatically cleared, indicating the main clock is off.
When enabling the main oscillator, the user must initiate the main oscillator counter with a value corresponding to
the startup time of the oscillator. This startup time depends on the crystal frequency connected to the main
oscillator.
When the MOSCEN bit and the OSCOUNT are written in CKGR_MOR to enable the main oscillator, the MOSCS
bit in PMC_SR (Status Register) is cleared and the counter starts counting down on the slow clock divided by 8
from the OSCOUNT value. Since the OSCOUNT value is coded with 8 bits, the maximum startup time is about 62
ms.
When the counter reaches 0, the MOSCS bit is set, indicating that the main clock is valid. Setting the MOSCS bit in
PMC_IMR can trigger an interrupt to the processor.
The Main Oscillator features a Main Clock frequency counter that provides the quartz frequency connected to the
Main Oscillator. Generally, this value is known by the system designer; however, it is useful for the boot program to
configure the device with the correct clock speed, independently of the application.
The Main Clock frequency counter starts incrementing at the Main Clock speed after the next rising edge of the
Slow Clock as soon as the Main Oscillator is stable, i.e., as soon as the MOSCS bit is set. Then, at the 16th falling
edge of Slow Clock, the MAINRDY bit in CKGR_MCFR (Main Clock Frequency Register) is set and the counter
stops counting. Its value can be read in the MAINF field of CKGR_MCFR and gives the number of Main Clock
cycles during 16 periods of Slow Clock, so that the frequency of the crystal connected on the Main Oscillator can
be determined.
Main Oscillator Startup Time
Main Oscillator Control
Main Clock Frequency Counter
XIN
SAM7S Microcontroller
XOUT
1K
GND
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
188
Related parts for AT91SAM7S256D-AU
Image
Part Number
Description
Manufacturer
Datasheet
Request
R
Part Number:
Description:
KIT EVAL FOR ARM AT91SAM7S
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU, MPU & DSP Development Tools KICKSTART KIT ATMEL AT91SAM7S
Manufacturer:
IAR Systems
Part Number:
Description:
MCU ARM9 64K SRAM 144-LFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM7 MCU FLASH 256K 100LQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM9 MPU 217-LFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU ARM9 ULTRA LOW PWR 217-LFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU ARM9 324-TFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC MCU ARM9 SAMPLING 217CBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM9 MCU 217-LFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM9 MCU 208-PQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU ARM 512K HS FLASH 100-LQFP
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
MCU ARM 512K HS FLASH 100-TFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM9 MCU 200 MHZ 324-TFBGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM MCU 16BIT 128K 256BGA
Manufacturer:
Atmel
Datasheet:
Part Number:
Description:
IC ARM7 MCU 32BIT 128K 64LQFP
Manufacturer:
Atmel
Datasheet: