JN516X Datasheet, PDF (16/94 Pages) NXP Semiconductors – IEEE802.15.4 Wireless Microcontroller

4 Memory Organisation
This section describes the different memories found within the JN516x. The device contains Flash, RAM, and
EEPROM memory, the wireless transceiver and peripherals all within the same linear address space.
Unpopulated
0xFFFFFFFF
0xF0008000
RAM
0x04000000
Peripherals
0x02000000
Flash & EEPROM Registers
0x01000000
0x000C0000
FLASH
Applications
Code
(256KB)
0x00080000
0x00000000
FLASH Boot Code 8K
Figure 5: JN5168 Memory Map
4.1 FLASH
The embedded Flash consists of 2 parts: an 8K region used for holding boot code, and a 256K region (JN5168) used
for application code. The maximum number of write cycles or endurance is, 10k guaranteed and typically 100k, while
the data retention is guaranteed for at least 10 years. The boot code region is pre-programmed by NXP on supplied
parts, and contains code to handle reset, interrupts and other events (see section 7). It also contains a Flash
Programming Interface to allow interaction with the PC-based Flash Programming Utility which allows user code
compiled using the supplied SDK to be programmed into the Application space. For further information, see the
application note, Flash Programmer User Guide.[9]
4.2 RAM
The JN516x devices contain up to 32Kbytes of high speed RAM, which can be accessed by the CPU in a single clock
cycle. It is primarily used to hold the CPU Stack together with program variables and data. If necessary, the CPU can
execute code contained within the RAM (although it would normally just execute code directly from the embedded
Flash). Software can control the power supply to the RAM allowing the contents to be maintained during a sleep
period when other parts of the device are un-powered, allowing a quicker resumption of processing once woken.
4.3 OTP Configuration Memory
The JN516x devices contain a quantity of One Time Programmable (OTP) memory as part of the embedded Flash
(Index Sector). This can be used to securely hold such things as a user 64-bit MAC address and a 128-bit AES
security key. A limited number of further bits are available for customer use for storage of configuration or other
information. A default the 64-bit MAC address is pre-programmed by NXP on supplied parts; however customers can
use their own MAC address and override the default one. The user MAC address and other data can be written to the
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JN-DS-JN516x v1.1 Production
© NXP Laboratories UK 2013