From c5fe338125878d42ea8795417c1c06ee8b1f4053 Mon Sep 17 00:00:00 2001 From: Peter Date: Tue, 5 Mar 2024 10:43:23 +0800 Subject: [PATCH] New posts: _posts/2024-03-03-How-to-read-datasheets.md _posts/2024-03-05-UWAA-project-briefs-2024.md --- _posts/2024-03-03-How-to-read-datasheets.md | 20 +++++ _posts/2024-03-05-UWAA-project-briefs-2024.md | 87 +++++++++++++++++++ 2 files changed, 107 insertions(+) create mode 100644 _posts/2024-03-03-How-to-read-datasheets.md create mode 100644 _posts/2024-03-05-UWAA-project-briefs-2024.md diff --git a/_posts/2024-03-03-How-to-read-datasheets.md b/_posts/2024-03-03-How-to-read-datasheets.md new file mode 100644 index 0000000..26e587d --- /dev/null +++ b/_posts/2024-03-03-How-to-read-datasheets.md @@ -0,0 +1,20 @@ +--- +title: How to read datasheets +author: peter +date: 2024-03-03 01:10:38 +0800 +categories: [Blogging] # Blogging | Electronics | Programming | Mechanical +tags: [getting started] # systems | embedded | rf | microwave | electronics | solidworks | automation +# image: assets/img/2024-03-03-How-to-read-datashee/preview.png +--- + +General advice on how to read a datasheet + +## Digital pins + +### Inverted/Active low/NOT + +A pin which is active low is typically designated with a `/` or an overbar + +For example: /CS or CS + +A common example is the chip select (/CS) pin on devices with SPI, where the chip select must be low for the SPI on the chip to become active. When it it high, it is idle. diff --git a/_posts/2024-03-05-UWAA-project-briefs-2024.md b/_posts/2024-03-05-UWAA-project-briefs-2024.md new file mode 100644 index 0000000..7f423f3 --- /dev/null +++ b/_posts/2024-03-05-UWAA-project-briefs-2024.md @@ -0,0 +1,87 @@ +--- +title: UWAA project briefs 2024 +author: peter +date: 2024-03-05 10:40:20 +0800 +categories: [UWAA] # Blogging | Electronics | Programming | Mechanical +tags: [electronics, projects] # systems | embedded | rf | microwave | electronics | solidworks | automation +# image: assets/img/2024-03-05-UWAA-project-briefs-/preview.png +toc: true +--- + +Updating this as I add new projects this year. + +# Telemetrum ground station + +The Telemetrum's Teledongle ground station is out of stock everywhere. We should make our own. + +## Success criteria + +- Receive signals from the [Telemetrum](https://altusmetrum.org/TeleMetrum/) flight computer over a distance of at least 10 kft. +- Send data to a computer over USB virtual COM port in a format which can be interpreted in real time by the [AltosUI flight monitoring software](https://altusmetrum.org/AltOS/). + +## Scope + +- Make a PCB which contains a cheap microcontroller with USB support and the CC12xx or CC11xx radio transceiver. + - Make sure the PCB has mounting holes so it can fit into a case. + - Use an SMA connector. +- Create software to copy the data from the receiver to the computer over USB through an intermediate MCU. + +## Hints and notes + +- You must read this [protocol specification](https://altusmetrum.org/AltOS/doc/telemetry.html) for the AltusMetrum devices. Luckily, the Teledongle does minimal processing of the raw data, it only encodes it into an ASCII format before transmitting it over serial. +- You should look at the schematics and PCB layout for the Teledongle for inspiration https://altusmetrum.org/TeleDongle/. + - I advise you don't use the NXP LPC11U14 since a cheaper microcontroller can do well +- [!] PRO TIP: Use JLCPCB's part library to save on money! It tends to be cheaper per unit than buying from distributors online since JLC buys the parts at wholesale prices. + - You should consider using the [basic parts library](https://jlcpcb.com/parts/basic_parts) to place passives (resistors, capacitors). On Altium, all components in this library will have a `JLC_PN` attribute. + - Using extended parts outside the basic library list will incur a $3 USD fee per unique part, but when assembling 5 boards this still beats distributor prices. Of course, if a part is in the basic library it should be used if possible + - You may decide to use this alternative site to look up parts since JLC's parametric search isn't great https://yaqwsx.github.io/jlcparts/ + - Try to place all/as many components on one side of the board only so you can use economic PCBA, which only places parts on one side. + - Feel free to ask me for Altium training, and I will probably need to talk about RF design considerations + +## Future development + +- Make this a module card which can go into a standalone battery powered ground station which does not need a laptop to use. This can be helpful if our laptops run out of energy and there are no generators. + +# Analog video transmitter + +## Success criteria + +- Receive at least 1 minute of video over a 10 kft LOS distance + +## Scope + +- Make a prototype setup to transmit and receive analog or digital video +- Use a raspberry pi to overlay text containing telemetry such as altitude, position, etc. +- Does not need to be a PCB yet + +## Hints and notes + +- To be honest, I am not quite sure how this stuff works and I'm interested in learning as well +- Two ways I can see this being done: + - 1. Use a project like wifibroadcast[[1](https://befinitiv.wordpress.com/wifibroadcast-analog-like-transmission-of-live-video-data/)][[2](https://hackaday.com/2015/06/13/wifibroadcast-makes-wifi-fpv-video-more-like-analog/)] which transmits digital video. Check out the link for more information. + - 2. Use a COTS analog 2.4 GHz video transmitter and receiver. Search 2.4 GHz video transmitter for examples. The TX6722 and RX6788 appears to be a common combination for 2.4 GHz band. + - Consider the differences in quality, error handling and bandwidth required when deciding between analog and digital video +- I'll update this once we get past a prototype + +# Software defined gnss receiver + +## Success criteria + +- Get position and altitude of the rocket through all stages of flight, including stages which exceed the velocity and/or altitude limitations of commercial GNSS receivers (510 m/s, 59,000 ft. See: [Coordinating Committee for Multilateral Export Controls](https://en.wikipedia.org/wiki/Coordinating_Committee_for_Multilateral_Export_Controls?&useskin=vector)) + +# Scope + +- Make a prototype/MVP system for doing this. It doesn't need to fit into a rocket or require self-powering at this current design phase. I will update the project when we have an MVP working. +- Test doing the post-processing on a single board computer. +- Record enough data from launch to landing + +# Hints and other notes + +- Capture raw [IQ](https://en.wikipedia.org/wiki/In-phase_and_quadrature_components?&useskin=vector) data from an SDR and do the post-processing in something like [GNSS SDR](https://github.com/gnss-sdr/gnss-sdr). Select an appropriate SDR which can digitize the L1 C/A GPS signal +- This exists https://www.rtl-sdr.com/rtl-sdr-tutorial-gps-decoding-plotting/, but it seems to require a computer with windows installed to process the data. + +# Future development + +- Miniaturize this setup and add a power system for use on a rocket +- Make a custom RF frontend specialized for the GNSS signals which is cheaper than buying an SDR +- Is it possible to use an FPGA to process this signal in real-time? (It's apparently really hard to do... I searched and the latest real-time implementation is from 2013)