4.2 Software Setup

Most code examples releases contain two software configurations – free and pro. The pro configuration is setup to use the high-level optimizations of the MPLAB XC8 Compiler, which require a software license, while the free configuration is compiled with only basic optimizations. Both configurations function identically, except for code size and speed improvements from the higher-level optimizations, as shown in Table 4-1.

However, two additional configurations were created for this example. The gas sensor on the Ammonia Click requires a 24-hour warmup time before reaching stable operation. The microcontroller alone can't differentiate a brief power glitch from a long power outage, so the 24-hour sensor warmup is enforced on start-up. However, this is unacceptable for development, so two alternate configurations, develop and develop_no_cksm, were created to accelerate start-up. These configurations also allow the system to start with self-test failures, which is important during development.

In develop_no_cksm, a dummy checksum value (0x87654321) is inserted into the firmware rather than using the Hexmate utility to add one to the output file, which is required since the inserted checksum causes issues when compiling for debugging. The table below shows a summary of the differences between the software configurations.