8 Set up and use OTA (Over The Air) Configuration
If the configuration parameter MPC_IO enables the CONFIG pin, an interrupt is used to send the current
configuration data in an SND-NR (C=0x44) message, and listen for a configuration message. The configuration
message from the gateway to the MPC can be either SND-UD (C=0x43) or SND-NR. The length of the listening
window can be configured by the configuration parameter PACKET_TIMEOUT.
Every time you pull the CONFIG pin low, the MPC1 module goes through the below process automatically:
Figure 3 – OTA123 flow
For a normal OTA123 update-cycle you will go through the above flowchart 3 (or 4) times:
Step 1: When CONFIG is activated the current configuration memory is sent from the MPC in an SND-NR
message using CI = 0xAA. Application data is the full dump of the configuration memory. The MPC1 is listening for
an SND-UD message, but will time out and go back to sleep.
Step 2: The MPC will also this time send an SND-NR message with the configuration memory. The gateway must
now be set up to respond to this message with an SND-UD message (SND-NR also accepted). The SND-UD
message can be formatted in two ways, leading to different actions on the MPC:
1. CI = 0xAB. The application data must contain the updated configuration parameters. You can send only the
bytes changed or the full configuration memory. When the MPC receives this message it will update
configuration memory accordingly.
2. CI = 0xAC. The application data is not read by the MPC. Module will reset.
Step 2 must be ran twice if the configuration parameters updated needs a reset to take effect, first with CI=0xAB,
then with CI=0xAC.
Step 3: This step is optional, but since the MPC sends the configuration memory in an SND-NR message when the
CONFIG pin is activated, then this can be used to read back the configuration after the update to confirm that the
result is as expected.
Warning!: If some of the configurations are changed un-intentionally to illegal values, it can set the module
into a not recoverable, nonworking condition. Currently there is no filter on permitted values.
Note! The module does not support encrypted messages for the OTA123 update procedure.
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