EM357-RTR datasheet(30/241 Pages) SILABS

30 / 241 page

Rev 1.3

5.2.1. Flash Memory

5.2.1.1. Flash Overview

The EM351 provides a total of 132 kB of flash memory and the EM357 provides a total of 196 kB of flash memory.

The flash memory is provided in three separate blocks:



Main Flash Block (MFB)



Fixed Information Block (FIB)



Customer Information Block (CIB)



The MFB is divided into 2048-byte pages. The EM351 has 64 pages and the EM357 has 96 pages. The CIB is a

single 2048-byte page. The FIB is a single 2048-byte page. The smallest erasable unit is one page and the

smallest writable unit is an aligned 16-bit half-word. The flash is rated to have a guaranteed 20,000 write/erase

cycles. The flash cell has been qualified for a data retention time of >100 years at room temperature.

Flash may be programmed either through the Serial Wire/JTAG interface or through bootloader software.

Programming flash through Serial Wire/JTAG requires the assistance of RAM-based utility code. Programming

through a bootloader requires Ember software for over-the-air loading or serial link loading.

5.2.1.2. Main Flash Block

The start of the MFB is mapped to both address 0x00000000 and address 0x08000000 in normal boot mode, but is

mapped only to address 0x08000000 in FIB monitor mode (see also "7.5. Boot Configuration" on page 53).

Consequently, it is recommended that software intended to execute from the MFB is designed to operate from the

upper address, 0x08000000, since this address mapping is always available in all modes.

The MFB stores all program instructions and constant data. A small portion of the MFB is devoted to non-volatile

token storage using the Ember Simulated EEPROM system.

5.2.1.3. Fixed Information Block

The 2 kB FIB is used to store fixed manufacturing data including serial numbers and calibration values. The start of

the FIB is mapped to address 0x08040000. This block can only be programmed during production by Silicon Labs.

The FIB also contains a monitor program, which is a serial-link-only way of performing low-level memory accesses.

In FIB monitor mode (see "7.5. Boot Configuration" on page 53), the start of the FIB is mapped to both address

0x00000000 and address 0x08040000 so the monitor may be executed out of reset.

5.2.1.4. Customer Information Block

The 2048 byte CIB can be used to store customer data. The start of the CIB is mapped to address 0x08040800.

The CIB cannot be executed.

The first eight half-words of the CIB are dedicated to special storage called option bytes. An option byte is a 16 bit

quantity of flash where the lower 8 bits contain the data and the upper 8 contain the inverse of the lower 8 bits. The

upper 8 bits are automatically generated by hardware and cannot be written to by the user, see Table 5.1.

The option byte hardware also verifies the inverse of each option byte when exiting from reset and generates an

error, which prevents the CPU from executing code, if a discrepancy is found. All of this is transparent to the user.

EM357-RTR Folha de dados(PDF) 30 Page - Silicon Laboratories