Rainbow Electronics W79E8213R - Manual (Page 65)

Preliminary W79E8213/W79E8213R Data Sheet
Publication Release Date: July 11, 2008
- 65 - Revision A2
14. NVM MEMORY
The W79E8213 series have NVM data memory of 128 bytes for customer’s data store used. The NVM
data memory has 8 pages area and each page of 16 bytes.
The NVM memory can be read/write by customer program to access. Read NVM data is by MOVC
A,@A+DPTR instruction, and write data is by SFR of NVMADDRL, NVMDATA and NVMCON. Before
write data to NVM memory, the page must be erased by providing page address on NVMADDRL,
which address of On-Chip Code Memory space will decode, then set EER of NVMCON.7. This will
automatically hold fetch program code and PC Counter, and execute page erase. After finished, this
bit will be cleared by hardware. The erase time is ~ 5ms.
For writing data to NVM memory, user must set address and data to NVMADDRL and NVMDATA,
then set EWR of NVMCON.6 to initiate nvm data write. The uC will hold program code and PC
Counter, and then write data to mapping address. Upon write completion, the EWR bit will be cleared
by hardware, the uC will continue execute next instruction. The program time is ~50us.
Figure 14-1: W79E8213 Memory Map