AT91SAM7SE256-AU Atmel, AT91SAM7SE256-AU Datasheet - Page 380

• Manufacturer Part Number: AT91SAM7SE256-AU
• Description: IC ARM7 MCU FLASH 256K 128-LQFP
• Manufacturer: Atmel
• Series: AT91SAMr

Specifications of AT91SAM7SE256-AU

• Core Processor: ARM7
• Core Size: 16/32-Bit
• Speed: 55MHz
• Connectivity: EBI/EMI, I²C, SPI, SSC, UART/USART, USB
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 88
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 32K 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: 128-LQFP
• Processor Series: AT91SAMx
• Core: ARM7TDMI
• Data Bus Width: 32 bit
• Data Ram Size: 32 KB
• Interface Type: SPI, TWI, USART
• Maximum Clock Frequency: 55 MHz
• Number Of Programmable I/os: 88
• Number Of Timers: 2
• Operating Supply Voltage: 3 V to 3.6 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: JTRACE-ARM-2M, KSK-AT91SAM7S-PL, MDK-ARM, RL-ARM, ULINK2
• Development Tools By Supplier: AT91SAM-ICE, AT91-ISP, AT91SAM7SE-EK
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• Controller Family/series: AT91SAM7xxxxx
• No. Of I/o's: 88
• Ram Memory Size: 32KB
• Cpu Speed: 48MHz
• No. Of Timers: 3
• Rohs Compliant: Yes
• For Use With: AT91SAM7SE-EK - EVAL BOARD FOR AT91SAM7SEAT91SAM-ICE - EMULATOR FOR AT91 ARM7/ARM9
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

33.7
33.7.1
33.7.2
33.7.3
33.7.4
380
Master Mode
AT91SAM7SE512/256/32 Preliminary
Definition
Application Block Diagram
Programming Master Mode
Transmitting Data
The Master is the device which starts a transfer, generates a clock and stops it.
Figure 33-5. Master Mode Typical Application Block Diagram
The following registers have to be programmed before entering Master mode:
After the master initiates a Start condition, it sends a 7-bit slave address, configured in the Mas-
ter Mode register (DADR in TWI_MMR), to notify the slave device. The bit following the slave
address indicates the transfer direction (write or read). If this bit is 0, it indicates a write operation
(transmit operation). If the bit is 1, it indicates a request for data read (receive operation).
The TWI transfers require the slave to acknowledge each received byte. During the acknowl-
edge clock pulse, the master releases the data line (HIGH), enabling the slave to pull it down in
order to generate the acknowledge. The master polls the data line during this clock pulse and
sets the NACK bit in the status register if the slave does not acknowledge the byte. As with the
other status bits, an interrupt can be generated if enabled in the interrupt enable register
(TWI_IER). After writing in the transmit-holding register (TWI_THR), the transmission will start
as soon as the bus is free. The data is shifted in the internal shifter and when an acknowledge is
detected, the TXRDY bit is set until a new write in the TWI_THR (see
The master generates a stop condition to end the transfer.
1. DADR (+ IADRSZ + IADR if a 10 bit device is addressed): The device address is used
2. CKDIV + CHDIV + CLDIV: Clock Waveform.
3. SVDIS: Disable the slave mode.
4. MSEN: Enable the master mode.
AT91 (Host)
with TWI
to access slave devices in read or write mode.
Figure 33-7 on page
6222B–ATARM–26-Mar-07
381).