4. Memory

The Panel-Card is equipped with 32-Bit CPU-bus which is not exported on the connectors but only used internally.

4.1. NOR Flash

The Panel-Card is equipped with a 16 MB or 64 MB NOR flash with 100000 erase and write cycles. It is organized in 128KB blocks. Customer specific adaptations are possible up to 128 MB on-board NOR flash. It is connected to chip select zero (NCS0) of the micro-controller.

The flash memory is made up of 1 or 2 ICs which have separated address spaces (see Appendix C, Address Map (Physical Address Space)).

Typically NOR flash is organized in blocks, similar to hard disks. Typical block sizes are 64, 128, 256 KB. NOR flash can be read and written randomly. This makes it possible to use NOR flash as execute in place (XIP) memory. To erase already written data, the whole block containing the data has to be erased.

NOR flash is subject to limited write and erase cycles. These are typically 100.000 cycles per block. So it is highly recommended to use wear levelling file systems.

4.2. SDRAM

The Panel-Card is equipped with 64MB SDRAM. Customer specific adaptations allow configurations up to 128MB. The SDRAM is connected to chip select one (NCS1) of the micro-controller.

SDRAM is volatile memory which allows random access to any location of its memory area. SDRAM has a synchronous interface. This means that it waits for a clock signal before responding to its control inputs, therefore it is synchronized with the CPU bus. The clock is used to drive a finite state machine in the chip, which allows to accept new instructions, before the previous one has finished executing.

4.3. EEPROM

The Panel-Card is equipped with a 256 bytes EEPROM, connected to the TWI (I2C).

EEPROM stands for Electrically Erasable Programmable Read-Only Memory and is non-volatile memory, which is used to store small amounts of data like calibration or configuration data. EEPROMS are byte-wise erasable, thus allowing true random access.

4.4. SRAM

The Panel-Card's micro-controller is equipped with 160 KB internal SRAM. The internal SRAM can be accessed in one bus cycle and may be used for time critical sections of code or interrupt handlers.

4.5. DataFlash

The Panel-Card 57 and Panel-Card 70 are equipped with 128 KB DataFlash™.

DataFlash is a Atmel® proprietary interface and is compatible to the SPI standard. Similar to other flash chips it can be addressed page orientated and is available in sizes up to 8MB. Furthermore it is a possible boot media for the microcontroller.