Khadas VIM2 v1.4 SBC Gets Bluetooth 5, Thermal Improvements, a Larger SPI Flash

Announced in summer of 2017, Khadas VIM2 was the first Amlogic S912 development board, and I had the chance to review the board with a dual DTV tuner add-on board shortly after launch, eventually explaining how to use VIM2 as a live TV streaming server in Android.

Shenzhen Wesion has however recently launched Khadas VIM2 v1.4 with various improvements they neatly describe in a PDF document.

Khadas VIM2 v1.4
Khadas VIM2 v1.4 vs v1.2 – Click to Enlarge

Before I go through the main changes, I’d like to remind readers there are three versions of Khadas VIM2 (v1.2) boards:

  • VIM2 Basic – 2GB DDR4, 16GB eMMC flash, Ampak AP6356S wireless module with 802.11 b/g/n/ac WiFi 5, and Bluetooth 4.1 connectivity
  • VIM2 Pro – 3GB DDR4, 32GB eMMC flash, Ampak AP6359SA wireless module with 802.11 b/g/n/ac with RSDB and Bluetooth 4.2 connectivity
  • VIM2 Max – 3GB DDR4, 64GB eMMC flash, Ampak AP6359SA wireless module with 802.11 b/g/n/ac with RSDB and Bluetooth 4.2 connectivity

One of the first change in VIM2 v1.4 is the update of AP6359SA module to AP6398S which gives VIM2 Pro/Max support for Bluetooth 5.0. VIM2 basic gets the original Ampack AP6356S module.

Khadas VIM2 Thermal DesignKhadas VIM2 v1.2 board thermal design was, let’s say… not quite optimal, especially with the optional DIY case, as the fan would just push hot air against a side without any ventilation holes. This would lead to overheating due to poor heat dissipation and making the fan work more than necessary, in turn generating unnecessary noise. So for VIM2 v1.4, the company redesigned the heatsink and changed to a quieter “almost silent” 3705 cooling fan controlled by PWM instead of GPIOs, as well as directing the hot air to the button holes.

Another improvement was to increase the SPI flash capacity from 2Mbit to 16Mbit which should allow for more flexibility and features in the bootloader. Other changes are more a matter of moving ports around, and/or make some adjustment for the new heatsink. For example, the Ethernet transformer was changed to a thinner one  (Pulse H5120NL) to make room for the heatsink. The fan header and RTC header were so moved around, and the VIN port close to the USB-C port was replaced by XPWR pads on the side of the board to connect an external power switch. The “F” button can also be used to easily enter upgrade mode by pressing it 3 times within 2 seconds, just like in Khadas Edge.

Software had to be changed as well since the fan now uses PWM to control the speed instead of a GPIO to turn it on and off, and the SPI flash is larger. But luckily the same firmware images can be used on v1.2 and v1.4 since each board stores a Version ID which will be detected at boot time.

The new Khadas VIM2 v1.4 SBC can be purchased for $99.90, $119.90, and $139.90 on Khadas store for respectively the Basic, Pro, and Max versions.

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