SAM7SE256 Atmel Corporation, SAM7SE256 Datasheet - Page 220

• Manufacturer Part Number: SAM7SE256
• Manufacturer: Atmel Corporation

Specifications of SAM7SE256

• Flash (kbytes): 256 Kbytes
• Pin Count: 144
• Max. Operating Frequency: 48 MHz
• Cpu: ARM7TDMI
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 88
• Ext Interrupts: 88
• Usb Transceiver: 1
• Usb Speed: Full Speed
• Usb Interface: Device
• Spi: 1
• Twi (i2c): 1
• Uart: 3
• Ssc: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 384
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 32
• Self Program Memory: NO
• External Bus Interface: 1
• Dram Memory: sdram
• Nand Interface: Yes
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8/3.3
• Operating Voltage (vcc): 3.0 to 3.6
• Fpu: No
• Mpu / Mmu: Yes / No
• Timers: 3
• Output Compare Channels: 3
• Input Capture Channels: 3
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: No

24.3
24.3.1
24.3.2
220
Functional Description
SAM7SE512/256/32
Write Access
Read Access
A page in NAND Flash and SmartMedia memories contains an area for main data and an addi-
tional area used for redundancy (ECC). The page is organized in 8-bit or 16-bit words. The page
size corresponds to the number of words in the main area plus the number of words in the extra
area used for redundancy.
The only configuration required for ECC is the NAND Flash or the SmartMedia page size
(528/1056/2112/4224). Page size is configured setting the PAGESIZE field in the ECC Mode
Register (ECC_MR).
ECC is automatically computed as soon as a read (00h)/write (80h) command to the NAND
Flash or the SmartMedia is detected. Read and write access must start at a page boundary.
ECC results are available as soon as the counter reaches the end of the main area. Values in
the ECC Parity Register (ECC_PR) and ECC NParity Register (ECC_NPR) are then valid and
locked until a new start condition occurs (read/write command followed by address cycles).
Once the flash memory page is written, the computed ECC code is available in the ECC Parity
Error (ECC_PR) and ECC_NParity Error (ECC_NPR) registers. The ECC code value must be
written by the software application in the extra area used for redundancy.
After reading the whole data in the main area, the application must perform read accesses to the
extra area where ECC code has been previously stored. Error detection is automatically per-
formed by the ECC controller. Please note that it is mandatory to read consecutively the entire
main area and the locations where Parity and NParity values have been previously stored to let
the ECC controller perform error detection.
The application can check the ECC Status Register (ECC_SR) for any detected errors.
It is up to the application to correct any detected error. ECC computation can detect four differ-
ent circumstances:
ECC Status Register, ECC Parity Register and ECC NParity Register are cleared when a
read/write command is detected or a software reset is performed.
For Single-bit Error Correction and Double-bit Error Detection (SEC-DED) hsiao code is used.
32-bit ECC is generated in order to perform one bit correction per 512/1024/2048/4096 8- or 16-
• No error: XOR between the ECC computation and the ECC code stored at the end of the
• Recoverable error: Only the RECERR flag in the ECC Status register (ECC_SR) is set. The
• ECC error: The ECCERR flag in the ECC Status Register is set. An error has been detected
• Non correctable error: The MULERR flag in the ECC Status Register is set. Several
NAND Flash or SmartMedia page is equal to 0. No error flags in the ECC Status Register
(ECC_SR).
corrupted word offset in the read page is defined by the WORDADDR field in the ECC Parity
Register (ECC_PR). The corrupted bit position in the concerned word is defined in the
BITADDR field in the ECC Parity Register (ECC_PR).
in the ECC code stored in the Flash memory. The position of the corrupted bit can be found
by the application performing an XOR between the Parity and the NParity contained in the
ECC code stored in the flash memory.
unrecoverable errors have been detected in the flash memory page.
6222F–ATARM–14-Jan-11