Main Memory Page Program Through Buffer Sector Protection: Along with all above read and write operations there are few other commands for sector protection. Sector Protection Register is used in order to specify the sectors, which is to be protected or unprotected. There are also three more commands available to program, read, erase Sector Protection Register. Sector protection can be achieved in two ways either by software or by hardware. Once WP is asserted, the sectors specified by Sector Protection Register will be protected against any program or erase operation.
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Main Memory Page Program Through Buffer Sector Protection: Along with all above read and write operations there are few other commands for sector protection. Sector Protection Register is used in order to specify the sectors, which is to be protected or unprotected. There are also three more commands available to program, read, erase Sector Protection Register.
Sector protection can be achieved in two ways either by software or by hardware. Once WP is asserted, the sectors specified by Sector Protection Register will be protected against any program or erase operation. In case if any program or erase operation command is issued while WP pin is asserted, the corresponding command will be ignored by the device and it will return to IDLE state once the CS pin is deasserted. Sector Lockdown: The device comes with another feature called sector lockdown mechanism.
This mechanism allows individual sector of the device to be locked permanently so that it becomes read only. Once the sector of the device is locked it cannot be programmed, erased or unlocked again.
Similar to all other operations, the sector lockdown operation also achieved with the help of 4 opcodes. In order to lockdown particular sector of the device the Sector Lockdown Register must be written with proper value.
During the execution of sector lockdown command if device is powered down then the lockdown of the sector cannot be guaranteed. In this case user should read Sector Lockdown Register to determine status of appropriate status lockdown bits. Security Register: The device contains specialized security register which can be used for purposes like unique device serialization or locked key storage. The register comprised of total bytes. Out of these bytes, first 64 bytes are allocated as one time user programmable space.
Once these 64 bytes are programmed they cannot be reprogrammed. The remaining 64 bytes 64 to bytes are factory programmed by Atmel and will contain unique value for each device. These 64 bytes are also fixed and cannot be reprogrammed. To program security register device must be clocked with 4 byte opcode with correct sequence with asserting CS pin first.
Like other operations if device is powered down up during program cycle security register, then contents of user programmable 64 bytes of Security Register cannot be guaranteed. The program security register command uses SRAM buffer for processing. Hence the contents of the buffer will be altered from its previous state when this command is issued. The devices are initially shipped with page size set to bytes The user also has option of ordering device with bytes page size from factory.
For Power 2 page size to become effective, following steps must be followed: Program one time programmable configuration register using opcode sequence. Power cycle the device power down and power up again. This can be achieved with following operations. Those flags are as below: RXCIF: This flag is set when there are unread data in receive buffer and cleared when receive buffer is empty i. When interrupt is used this flag is cleared after data is read in receive complete interrupt routine.
Similarly this flag can be cleared by writing 1 to this bit. TXCIF: This flag is set when the entire frame in the transmit shift register has been shifted out and there are no new data in transmit buffer. This flag is cleared when corresponding interrupt vector is executed or it can be cleared by writing 1 to this bit. DREIF: This flag is one when transmit buffer is empty and zero when transmit buffer contains data to be transmitted and that has not yet been moved into shift register.
We will enable both receiver and transmitter. The rest of bits of this register are unused in master SPI mode. Of course, communication mode will be master SPI mode. We will keep data order bit as zero as we want MSB of data word to be transmitted first.
The default mode of dataflash is Mode 3, hence clock phase bit will be one. The higher nibble of this register contains baud rate generator scale factor. The -8 0b setting is reserved. The formulae for baud rate calculation as per datasheet are below.
We will use standard baud rate value as 1MHz for this example. I have left the rest of operations as homework for you guys. If you have any doubts for the same you can mention it in comments.
Faerr The device operates from a single power supply, 2. Therefore not possible to only program the first two bytes of the register and then pro- gram the remaining 62 bytes at a later time. Main Memory Page Read Opcode: Since the entire memory array erased, no address bytes need to be clocked into the device, and any data clocked in after the opcode will datashdet ignored To perform a buffer to main memory page program with built-in erase for the PUW Changed t from max To allow for simple in-system reprogrammability, the AT45DBD does not require high input voltages for programming. Being able to reprogram the Sector Protection Register with the sector protection enabled allows the user to temporarily disable the sector protection to an individual sector rather than dis- abling sector protection completely.
AT45DB642D-CNU ATMEL QFN-8 Memory
The dual-interface allows a dedicated serial interface to be connected to a DSP and a dedicated 8-bit interface to be connected to a microcontroller or vice versa. However, the use of either interface is purely optional. Its 69,, bits of memory are organized as 8, pages of 1, bytes binary page size or 1, bytes standard DataFlash page size each. The buffers allow receiving of data while a page in the main Memory is being reprogrammed, as well as writing a continuous data stream. EEPROM emulation bit or byte alterability is easily handled with a self-contained three step read-modifywrite operation.