What are the limits of the Iridium 9704 Launch Pad?

The Iridium® Certus® 9704 developer kit is the quickest way into IMT. It is a good tool to try things with; as a product, it runs into the limits below.

What it is

Limit 1: the processor has little memory

One IMT message can be 100 KB, more than three times the processor's RAM; Iridium's own reflector example notes that the board's RAM cannot hold a 100 KB message. In N3D's measurements, the Iridium library and the Arduino core take about 24 KB, leaving only a few KB for your program. Large-file transfer, over-the-air firmware updates and an outbox that survives power loss can each be squeezed in, but not all together. Running out of memory does not always crash the board either; data can be silently overwritten, which takes a long time to debug.

Limit 2: the examples are demos, not product firmware

Iridium's examples are meant for evaluation and learning, not long unattended operation:

• Examples such as the serial pass-through and the reflector wait for USB to be connected before they start, so the output can be watched on a computer.
• When a send fails, the reason is printed on the serial port; whether to send again is up to your program.
• Pending messages are not kept; after a restart they start over.

For a device that runs on its own outdoors, retries, storage that survives power loss and automatic restart when the program hangs all have to be added.

Limit 3: it ships tied to demo applications

The kit ships pre-provisioned with 12 months of demonstration airtime or 1,000 messages, whichever comes first, for Iridium's demo applications: messages go to a Blynk dashboard or are reflected back to the board through the Iridium gateway. According to Iridium, sending to your own application requires a subscription and new provisioning.

Limit 4: evaluation only, not commercial use

Ground Control's developer kit page states that it is for development, testing and evaluation only and is not approved for commercial deployment. A product for sale needs its own Iridium certification (see why 9704 products need certification). Iridium also says the kit is designed for developers to use on their own, without expecting them to need Iridium support.

Limit 5: battery and low temperature

• Battery: in two N3D rooftop tests, the 9704 started restarting by itself after about 2.2 MB had been transferred in each direction, at an average battery voltage of about 3.9 V, with about two thirds of the battery still left. The cause is still being confirmed with Iridium (see how to design power for the 9704).
• Low temperature: MetOcean has published an advisory that some 9704 modules do not operate reliably near or below 0°C. Early developer kits may be among them, so do not treat low-temperature test results as a basis for a product.

What it is best for

• Measuring signal, latency and power use where you plan to deploy.
• Learning the 9704's JSON serial protocol and checking your message format.
• Using Iridium's External Control Mode to drive the board's 9704 from your own processor while you build a prototype.