Troubleshooting Tips
Note
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Power and Communication Issues
PWR_EN
VCC power for the Swarm M138 modem is connected via a MIC94064 High-Side Power Switch:
- By default, the modem power is turned off
- Modem power can be enabled by pulling the PWR_EN pin high
- PWR_EN is connected to the MicroMod Processor - the exact pin depends on which Main Board and Processor Board are being used. Please see the table in the Product Manual - Hardware Overview section for more details
- Modem power can be disabled by pulling the PWR_EN pin low or leaving it unconnected
- The EN split pad jumper can be soldered closed to permanently enable modem power
The modem has three very bright LEDs on it. These light up when power is applied. If the LEDs are lit, then PWR_EN is high and the high-side switch is enabled.
Some MicroMod Processor Boards do not have a GPIO pin connected to PWR_EN. If you are using one of these boards, solder the EN jumper closed to power the modem
Power and UART Communication
If you are unable to power up your M138 modem and/or are unable to communicate with it, it may be because the M.2 contacts (gold fingers) are slightly out of alignment.
Remove the screws, remove the function board, re-insert it while pushing it gently over to one side, and replace the screws. If you are still unable to communicate with the modem, repeat the process and gently push to the other side as you re-insert the board. Tighten both screws a little at a time to prevent the board from 'walking' out of alignment. Please see the Product Manual - Hardware Assembly section for more details.
Swarm Satellite Communication
Swarm have provided excellent advice about ensuring a good satellite signal. Please see this guest blog post for more details:
You can find more useful information in the Satellite Transceiver Breakout - Swarm M138 - Hookup Guide:
Example9_ReceiveTest in our Swarm Satellite Arduino Library provides details on how to read the RSSI: