The GPS board mentioned in my latest blog has now been put through the reflow soldering oven. Only component missing now is the GPS receiver from uBlox. As it cannot tolerate the reflow soldering process, it will be soldered by hand during the weekend.
The initial test, applying power to the board (aka smoke test) was performed without incident. I will leave the “hello world”-test to the GPS team.
The only leaded component on the board is the connector used to program the processor. The GPS team specified an ATMEGA2560 processor, as it is equipped with 4 UARTs. The rest of the through-hole pads on the board are for discrete wires.
The GPS box will contain two GPS receivers.
The main GPS receiver is a Novatel model, kindly donated by Gomspace in Aalborg. This receiver is used in the companys nanosatellites, and should be able to maintain a position fix at the acceleration levels expected during the powered part of the Nexø II flight.
The secondary GPS is a uBlox receiver from their NEO8-series. We wish to find out if this receiver is able to maintain a position fix during powered flight, as this is a problem for most commercially available GPS receivers.
A barometric pressure sensor is also incorporated in the system. This MEMS sensor will be mounted in a connector shell, enabling us to place it outside the closed GPS box. We are interested in learning about it’s usability as an altitude indicator.
Below are a couple of pictures from the soldering process.
The GPS board with solder paste applied. Most of the passive components are placed. Photo: Bo Brændstrup.
Here all semiconductors have been placed as well. Only the connector for the uBlox antenna is missing. Photo: Bo Brændstrup.
The board immediately after reflow soldering. The fine pitch parts will need some rework, but there is no tombstoning. Photo: Bo Brændstrup.
2 Comments
Jan Heisterberg · 4th May 2017 at 9:24 am
Very interesting about the GPS receiver.
However, not everyone May be familier with the terms used: eg. Tombstoning. Further, even the proces og soldering paste or reflow soldering may be unknown.
Finally, the terms like UARTS need explaining.
I fully understand, that vyou may not wish to waste time on there details, but you could perhaps ADD an editor to the team to supply these details as links – onde made, future references are easy.
Bo Braendstrup · 4th May 2017 at 7:08 pm
Explaining all the terms and processes is beyond the scope of the short blog above.
It is written to provide information about what is (also) happening at CS right now.
I meticulously explain acronyms that are not expected to be commonly known to the average technical reader, especially acronyms we invent at CS. I expect GPS and UART to be commonly known acronyms.
The term “tombstoning” was deliberately included to arouse curiosity, and inspire readers lacking knowledge about the phenomenon to seek information on their own. As you have drawn attention to the phenomenon, I’ll provide a link to an explanation:
https://goo.gl/Ms2Rur
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