Develop a Dual-Bank Firmware Architecture
- Implementing a dual-bank system can help ensure that if a new firmware update fails, the system can roll back to the previous working version. Allocate separate memory banks for the active firmware and the backup version.
- Ensure that upon successful update validation, the new firmware is copied to the secondary bank and its integrity is verified.
#define FIRMWARE_BANK_A 0x08000000 // Primary Bank
#define FIRMWARE_BANK_B 0x08100000 // Secondary Bank
void switchToBankB() {
// Logic to boot from Bank B
}
Implement CRC or Checksum Verification
- Post-update, a verification process should occur to validate the integrity of the updated firmware. Use CRC or checksum hashes for this purpose during the update process.
- Pre-calculate the checksum of the newly downloaded firmware image and store it securely. After the update, calculate the checksum of the active firmware and compare it to the stored checksum.
#include <stdint.h>
uint32_t calculateCRC(uint8_t* data, size_t length) {
uint32_t crc = 0xFFFFFFFF;
for (size_t i = 0; i < length; i++) {
crc ^= data[i];
for (uint8_t j = 0; j < 8; j++) {
if (crc & 1)
crc = (crc >> 1) ^ 0xEDB88320;
else
crc >>= 1;
}
}
return ~crc;
}
bool verifyFirmware(uint8_t* firmware, size_t length, uint32_t expectedCRC) {
return calculateCRC(firmware, length) == expectedCRC;
}
Utilize Watchdog Timers for System Recovery
- A Watchdog Timer (WDT) should be employed to reset the system in case the firmware gets stuck due to a bad update. Configure the WDT such that it resets the system if the main loop does not service it regularly.
- Ensure that your bootloader or initialization code can detect if the reset was due to a WDT, and accordingly switch to a stable firmware bank if needed.
#include <WatchdogLibrary.h>
void setup() {
Watchdog.enable(4000); // 4 seconds WDT
}
void loop() {
// Your main loop code
Watchdog.reset(); // Reset WDT timer
}
Design a Safe Update Process with Rollback Mechanisms
- During the update process, maintain states to track the progress so that any interruption can be managed gracefully. This includes downloading, verifying, and writing firmware to memory.
- If the update process encounters any unforeseen issues, initiate a rollback to the previous firmware version stored in the secondary bank.
enum UpdateState {
IDLE,
DOWNLOADING,
VERIFYING,
INSTALLING,
COMPLETE,
FAILED
};
UpdateState currentState = IDLE;
void handleUpdate() {
// Logic to perform and track update
if (updateFails()) {
rollbackFirmware();
}
}
Log Update Processes and Errors
- Logging both successful and failed updates, along with the reasons for failure, helps diagnose and improve future updates. Store logs in non-volatile memory if available, ensuring persistence across reboots.
- Analyze these logs post-failure to identify patterns or issues in the update process that require addressing.
void logError(char* message) {
// Logic to store the log internally or send to a server
}
Implement User Feedback and Diagnostics
- Provide clear feedback mechanisms to the user or system administrators regarding the current update status and any errors that arise. This can be through LEDs, serial console, or a networked UI.
- Consider implementing a diagnostic mode that outputs detailed error states and allows for manual intervention if needed.
void provideFeedback(bool success) {
if (success) {
// Indicate success (e.g., blink LED green)
} else {
// Indicate failure (e.g., blink LED red)
}
}
