AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 749

• Manufacturer Part Number: AT91SAM7S256D-AU
• Description: ARM Microcontrollers - MCU 256K Flash SRAM 64K ARM based MCU
• Manufacturer: Atmel
• Series: SAM7S256r

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

40.25.2.2
40.25.2.3
40.25.2.4
40.25.2.5
40.25.3
40.25.3.1
40.25.4
40.25.4.1
Check the Channel Counter Register before writing the update register.
When Channel Period Register equals 0, the period update is not operational.
Do not write 0 in the period register.
In left aligned mode, the first start value of the counter is 0. For the other periods, the counter starts at 1.
None.
Setting Channel Duty Cycle Register (PWM_CDTYx) at 0 in center aligned mode or at 0 or 1 in left aligned mode
may change the polarity of the signal.
Do not set PWM_CDTYx at 0 in center aligned mode.
Do not set PWM_CDTYx at 0 or 1 in left aligned mode.
Erratic behavior of the CHIDx status bit in the PWM_SR Register. When a channel is disabled by writing in the
PWM_DIS Register just after enabling it (before completion of a Clock Period of the clock selected for the channel),
the PWM line is internally disabled but the CHIDx status bit in the PWM_SR stays at 1.
Do not disable a channel before completion of one period of the selected clock.
If an event (RTTINC or ALMS) occurs within the same slow clock cycle during which the RTT_SR is read, the cor-
responding bit might be cleared. This can lead to the loss of this event.
The software must handle the RTT event as an interrupt and should not poll RTT_SR.
Bad Serial clock generation on the 2nd chip select when SCBR = 1, CPOL = 1 and NCPHA = 0.
This occurs using SPI with the following conditions:
• Master Mode
• CPOL = 1 and NCPHA = 0
• Multiple chip selects are used with one transfer with Baud rate (SCBR) equal to 1 (i.e., when serial clock
• Transmitting with the slowest chip select and then with the fastest one, then an additional
Real Time Timer (RTT)
Serial Peripheral Interface (SPI)
frequency equals the system clock frequency) and the other transfers set with SCBR are not equal to 1
on output SPCK during the second transfer.
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround:
PWM: Update when PWM_CPRDx = 0
PWM: Counter Start Value
PWM: Constraints on Duty Cycle Value
PWM: Behavior of CHIDx Status Bits in the PWM_SR Register
RTT: Possible Event Loss when Reading RTT_SR
SPI: Bad Serial Clock Generation on 2nd Chip Select
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
pulse is generated
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