AT91SAM7S256C-MU Atmel, AT91SAM7S256C-MU Datasheet - Page 662

• Manufacturer Part Number: AT91SAM7S256C-MU
• Description: IC ARM7 MCU 32BIT 256K 64-QFN
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7S256C-MU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 55MHz
• Connectivity: I²C, SPI, SSC, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, DMA, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 64K x 8
• Voltage - Supply (vcc/vdd): 1.65 V ~ 1.95 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-VQFN Exposed Pad, 64-HVQFN, 64-SQFN, 64-DHVQFN
• Processor Series: AT91
• Core: ARM7TDMI
• Data Bus Width: 32 bit
• Data Ram Size: 64 KB
• Interface Type: SPI, TWI, USART, USB
• Maximum Clock Frequency: 55 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 5
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• For Use With: AT91SAM-ICE - EMULATOR FOR AT91 ARM7/ARM9AT91SAM7S-EK - KIT EVAL FOR ARM AT91SAM7S
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Details
• Other names: AT91SAM7S256-MU; AT91SAM7S256-MU

40.11.8
40.11.8.1
40.11.8.2
40.11.8.3
40.11.8.4
40.11.8.5
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AT91SAM7S Series Preliminary
Serial Peripheral Interface (SPI)
SPI: Bad tx_ready behavior when CSAAT = 1 and SCBR = 1
SPI: LASTXFER (Last Transfer) behavior
SPI: SPCK Behavior in Master Mode
SPI: Chip Select and Fixed Mode
SPI: Baudrate Set to 1
Use RTTINC as an increment for a software counter.
If the SPI is programmed with CSAAT = 1, SCBR(baudrate) = 1 and two transfers are performed
consecutively on the same slave with an IDLE state between them, the tx_ready signal does not
rise after the second data has been transferred in the shifter. This can imply for example, that
the second data is sent twice.
Do not use the combination CSAAT = 1 and SCBR = 1.
In FIXED Mode, with CSAAT bit set, and in “PDC mode” the Chip Select can rise depending on
the data written in the SPI_TDR when the TX_EMPTY flag is set. If for example, the PDC writes
a “1” in the bit 24 (LASTXFER bit) of the SPI_TDR, the chip select will rise as soon as the
TXEMPTY flag is set.
Use the CS in PIO mode when PDC mode is required and CS has to be maintained between
transfers.
SPCK pin can toggle out before the first transfer in Master Mode.
Problem Fix/Workaround
In Master Mode, MSTR bit must be set (in SPI_MR register) before configuring SPI_CSRx
registers.
In fixed Mode, if a transfer is performed through a PDC on a Chip select different from the Chip
select 0, the output spi_size sampled by the PDC will depend on the field, BITS (Bits per Trans-
fer) of SPI_CSR0 register, whatever the selected Chip select is. For example, if SPI_CSR0 is
configured for a 10-bit transfer whereas SPI_CSR1 is configured for an 8-bit transfer, when a
transfer is performed in Fixed mode through the PDC, on Chip select 1, the transfer will be con-
sidered as a HalfWord transfer.
If a PDC transfer has to be performed in 8 bits, on a Chip select y (y as different from 0), the
BITS field of the SPI_CSR0 must be configured in 8 bits, in the same way as the BITS field of
the CSRy Register.
When Baudrate is set at 1 (i.e. when serial clock frequency equals the system clock frequency)
and when the BITS field of the SPI_CSR register (number of bits to be transmitted) equals an
ODD value (in this case 9,11,13 or 15), an additional pulse will be generated on output SPCK.
Everything is OK if the BITS field equals 8,10,12,14 or 16 and Baudrate = 1.
None.
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
Problem Fix/Workaround
6175K–ATARM–30-Aug-10