The Forlinx OKMX6UL-C1 i.MX6UL development board

The demand for low power electronics is high as ever and new products are always hitting the market. The i.MX6UL series is another such chipset that is extremely useful for powering multimedia applications, especially the low power portable ones. So we decided to check out some of the small form factor boards readily available for development.
Picking a SoM (system-on-module) type i.MX6UL device is an option, but without a proper base board, it can get frustrating quickly. So here is a product of our choice – with fully supported set of peripherals on the base board, and a small form factor core board which can be plugged/unplugged – and most important, is low power and performs well with Linux. The Forlinx iMX6UL development board is one such good solution.

The OKMX6UL-C1 Development Board

Forlinx iMX6UL development board base board

It is a rather large development board. But the large form factor can be extremely useful. The problem with single board computers of the “credit card size” is that you cannot probe around and measure things. Nor can you really understand how the system works and produce your own customized boards. The large form factor here is excellent for really understanding the component level operation of every peripheral block on the board.

The board we have here has the following features:

Forlinx iMU6UL development board features
Development Boad Features (Source:
Forlinx iMU6UL core board features
Core Board Features (Source:

First Impressions

Important things first! The first impressions does not include what the board color is or Arduino compatibility. That is up to you. Here is what we consider first:


  • Schematics available?    YES
  • Linux kernel source ready to compile?    YES
  • Windows support?    NOT YET
  • u-boot source code available    NO
  • English support    YES
  • Board can be bricked with wrong firmware loading?    NO
  • Power supply options    5V input (regulated)
  • Peripheral drivers    YES
  • All peripherals clearly marked on board?    YES
  • Support for LCD displays + touch?    YES

So overall for a complex SoC, the development board seems to provide a really good platform to build applications on.

Note on power supply for the board

On first powering up the development board with the supplied power adapter, the board did NOT power up. This may happen to an OKMX6UL board that you have as well. The reason is that the supplied power adapter actually puts out about 5.5V when not loaded (even though it is rated at 5V). This is normal for many high current power adapters.

This prevents the board from turning on. Why? The reason can be noted in the schematic of the board power supply as noted here:

Forlinx iMX6UL Overvoltage protection
OKMX6UL power supply schematic (click to enlarge)

The OKMX6UL uses the 5V rail straight off the power adapter, which requires that your power adapter should be exactly 5V and should regulate well when loaded.

We tried 3 power adapters:

  1. One supplied by Forlinx: The power adapter (OC output voltage 5.5V) did not turn on the board at all because of over voltage protection as described in above image.
  2. A low cost generic 5V adapter: This adapter had an OC voltage of 4.8V and dropped when the board powered up, thus putting the board in a boot loop (not nice!).
  3. Another generic 5V adapter: This has an OC voltage of 5.1V and regulated well under load. The board booted up well and performed under full processing load (video playback).

So in short, what this tells you is that you should use regulated 5V power supply, preferably a bench power supply, when powering the board with an LCD panel connected (heavy load). The 5V input is not regulated again on the board itself and so you need to feed regulated 5V only for reliable operation.

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