NVM_SUM
checksum = (u16)NVM_SUM - checksum;
if (checksum != (u16) NVM_SUM) {
checksum = (u16) NVM_SUM - checksum;
if (checksum != (u16) NVM_SUM) {
checksum = (u16) NVM_SUM - checksum;
checksum = (u16) NVM_SUM - checksum;
if (checksum != (u16) NVM_SUM) {
checksum = (u16) NVM_SUM - checksum;