AT91SAM7S256D-AU Atmel, AT91SAM7S256D-AU Datasheet - Page 151

• 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

22. Peripheral DMA Controller (PDC)
22.1
22.2
Overview
The Peripheral DMA Controller (PDC) transfers data between on-chip serial peripherals such as the UART,
USART, SSC, SPI, MCI and the on- and off-chip memories. Using the Peripheral DMA Controller avoids processor
intervention and removes the processor interrupt-handling overhead. This significantly reduces the number of
clock cycles required for a data transfer and, as a result, improves the performance of the microcontroller and
makes it more power efficient.
The PDC channels are implemented in pairs, each pair being dedicated to a particular peripheral. One channel in
the pair is dedicated to the receiving channel and one to the transmitting channel of each UART, USART, SSC and
SPI.
The user interface of a PDC channel is integrated in the memory space of each peripheral. It contains:
The peripheral triggers PDC transfers using transmit and receive signals. When the programmed data is trans-
ferred, an end of transfer interrupt is generated by the corresponding peripheral.
Block Diagram
Figure 22-1. Block Diagram
• two 32-bit memory pointer registers (send and receive)
• two 16-bit transfer count registers (send and receive)
• two 32-bit registers for next memory pointer (send and receive)
• two 16-bit registers for next transfer count (send and receive)
Peripheral
Control
THR
RHR
Status & Control
PDC Channel 0
PDC Channel 1
Peripheral DMA Controller
Control
SAM7S Series [DATASHEET]
Controller
Memory
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