From 9d5bebfe9dc138028ba3b287ed0d7ce62b6c56f1 Mon Sep 17 00:00:00 2001 From: akuker <34318535+akuker@users.noreply.github.com> Date: Thu, 28 Apr 2022 18:02:52 -0500 Subject: [PATCH] Created Supercapacitor UPS (markdown) --- Supercapacitor-UPS.md | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 Supercapacitor-UPS.md diff --git a/Supercapacitor-UPS.md b/Supercapacitor-UPS.md new file mode 100644 index 0000000..c2bb7e0 --- /dev/null +++ b/Supercapacitor-UPS.md @@ -0,0 +1,25 @@ +# Background + +The RaSCSI service caches data in RAM. When power is pulled from a RaSCSI/Raspberry Pi setup, it is possible to lose some or all of this data. In order to allow a graceful shutdown of the RaSCSI service and the Raspberry Pi OS, a USP can be added to the assembly. This way, when power is removed, the Raspberry Pi will have enough saved power to properly shut down. + +# Prototype Phase: Dr. Scott M. Baker design + +Dr. Scott M. Baker has designed two different UPS versions that will work with the RaSCSI. He has generously made these available on this blog for other people to use. + + + +## Assembly +![image](https://user-images.githubusercontent.com/34318535/165860429-e71abe1e-e8b8-42eb-8194-94afd55ff2b6.png) + +For akuker's initial prototype, he started with the [gerber files](https://github.com/sbelectronics/ups/tree/master/gerbers/12v) provided by Dr. Baker. At the time of this writting, ATTiny85 chips are in very short supply. However, I was able to acquire some through [Amazon] in small volumes. (https://smile.amazon.com/gp/product/B06W9JBJJ6/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1) The rest of the parts were ordered from Digikey: +![image](https://user-images.githubusercontent.com/34318535/165860847-f07941f5-336a-48c2-bd18-9706a9f4d247.png) + +Note that for my initial prototype, I did not populate all of the connectors. I also did not populate the voltage dividers on the USB port (R15, R16, R17, R18). The "ORK" buck converter used by Dr. Baker was also not available. For one prototype, I used a [7805TV voltage regulator](https://www.sparkfun.com/datasheets/Components/LM7805.pdf). For the other, I bodged in a [LM2596S voltage regulator](https://www.ti.com/lit/ds/symlink/lm2596.pdf?ts=1651114146845&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLM2596%253Futm_source%253Dgoogle%2526utm_medium%253Dcpc%2526utm_campaign%253Dapp-null-null-GPN_EN-cpc-pf-google-wwe%2526utm_content%253DLM2596%2526ds_k%253DLM2596%2526DCM%253Dyes%2526gclid%253DCj0KCQjw06OTBhC_ARIsAAU1yOUmvCB1WjcI1iKPeRtjK6ZXnT-MiqXwZSRntonhIAZ8ne8dBUrtJYsaAkxREALw_wcB%2526gclsrc%253Daw.ds), which has a higher amperage rating. + +## Programming the ATTiny85 + +For programming the ATTin85, I followed these instructions: https://create.arduino.cc/projecthub/arjun/programming-attiny85-with-arduino-uno-afb829 + +# "Official" RaSCSI version + +For the RaSCSI, akuker will be focusing on the 12v version of Dr. Baker's UPS. A modified version of this is being designed and will be offered in the Tindie store (when it is ready). \ No newline at end of file