My lower-midrange Hubsan X4+ FPV drone got stuck in a tree in the middle of winter. We managed to knock it down a couple of months ago (the drone, not the tree), while there was still lots of snow to cushion the fall. After weathering the elements for over a month, it appeared to be mostly fine, except…one motor was seized. On the plus side – teardown excuse.
I confess this isn’t a full teardown. The 720p camera+transmitter board is hidden under the main controller board, and while it wouldn’t be too big an effort to expose it, I seem to be getting cautious in my older age. This stuff is small, and probably not up to many disassembly/reassembly cycles.
Figure 1 Drone, cover off. Yup, regular brushed DC motors. The video transmitter antenna is sticking out the rear of the drone (photo-right).
The main processor is an ST STM32F031K6, an ARM Cortex-M0 with the usual cadre of peripherals, as well as a motor-control block (the leftmost large chip in Figure 2). Although at the lower end of the ARM continuum, it’s doubtless more than powerful enough for this application. Amazing what $1 will buy you in a microcontroller these days.
The next major chip is an Invensense MPU-6050, which combines a three-axis gyro and accelerometer with onboard processing.
Chip #3 is labelled AMS29023, but I haven’t been able to find any information about it. Clearly though, it’s the 2.4 GHz RC receiver (the video transmitter uses 5.8 GHz).
I’ll wager the foam-covered part at the bottom of the board is a pressure sensor, as Hubsan claims height hold ability.
The ribbon cable at the top goes to the camera board, and to its right is a microSD socket for saving video and stills.
The PCB vias look strange, but maybe they always look like that and you just don’t notice it when a darker soldermask is used.
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