AT91SAM7S256C-MU Atmel, AT91SAM7S256C-MU Datasheet - Page 138

• 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

20.3.3
20.3.4
138
AT91SAM7S Series Preliminary
Read/Write Handshake
Device Operations
The read/write handshake is done by carrying out read/write operations on two registers of the
device that are accessible through the JTAG:
Access to these registers is done through the TAP 38-bit DR register comprising a 32-bit data
field, a 5-bit address field and a read/write bit. The data to be written is scanned into the 32-bit
data field with the address of the register to the 5-bit address field and 1 to the read/write bit. A
register is read by scanning its address into the address field and 0 into the read/write bit, going
through the UPDATE-DR TAP state, then scanning out the data.
Refer to the ARM7TDMI reference manuel for more information on Comm channel operations.
Figure 20-8. TAP 8-bit DR Register
A read or write takes place when the TAP controller enters UPDATE-DR state. Refer to the IEEE
1149.1 for more details on JTAG operations.
The write handshake is done by polling the Debug Comms Control Register until the R bit is
cleared. Once cleared, data can be written to the Debug Comms Data Register.
The read handshake is done by polling the Debug Comms Control Register until the W bit is set.
Once set, data can be read in the Debug Comms Data Register.
Several commands on the Flash memory are available. These commands are summarized in
Table 20-3 on page
is reading and writing the Debug Comms Registers.
TDI
• Debug Comms Control Register: DCCR
• Debug Comms Data Register: DCDR
• The address of the Debug Comms Control Register is 0x04.
• The address of the Debug Comms Data Register is 0x05.
The Debug Comms Control Register is read-only and allows synchronized handshaking
between the processor and the debugger.
– Bit 1 (W): Denotes whether the programmer can read a data through the Debug
– Bit 0 (R): Denotes whether the programmer can send data from the Debug Comms
Comms Data Register. If the device is busy W = 0, then the programmer must poll
until W = 1.
Data Register. If R = 1, data previously placed there through the scan chain has not
been collected by the device and so the programmer must wait.
r/w
4
Address
Address
Decoder
126. Commands are run by the programmer through the serial interface that
5
0
31
Debug Comms Control Register
Debug Comms Data Register
Data
32
6175K–ATARM–30-Aug-10
0
TDO