8-bit AVR Microcontrollers

NRWW – No Read-While-Write Section

The code located in the NRWW section can be read when the boot loader software is updating a page in the RWW section. When the boot loader code updates the NRWW section, the CPU is halted during the entire page erase or page write operation.

Table 1. Read-While-Write Features
Which Section does the Z-pointer Address During the Programming? Which Section can be Read During Programming? CPU Halted? Read-While-Write Supported?
RWW Section NRWW Section No Yes
NRWW Section None Yes No
Figure 1. Read-While-Write vs. No Read-While-Write
Figure 2. Memory Sections