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by cjketle
Sat Feb 27, 2021 8:28 am
Forum: General
Topic: Fuzix on the Raspberry Pi Pico
Replies: 77
Views: 3094

Re: Fuzix on the Raspberry Pi Pico

FYI if you are prototyping on a breadboard with (micro)SD cards it is easy enough (with care) to solder a length of .1" pin header directly to the card adapter (see att with pull up resistors). This keeps the lead length to a minimum. Need to use minimum amount of time and solder to avoid melti...
by cjketle
Tue Nov 24, 2020 12:25 pm
Forum: Interfacing (DSI, CSI, I2C, etc.)
Topic: dtoverlay for CAN bus NON MCP2515
Replies: 1
Views: 134

Re: dtoverlay for CAN bus NON MCP2515

The TI chip you refer to is only the CAN bus interface, not the controller - that is it matches the CAN bus logic levels and protections to the logic levels of the Pi. You will need an additional controller - the MCP2515 is the obvious one as there is already software support for it. Not clear wheth...
by cjketle
Sat Sep 26, 2020 3:32 pm
Forum: Troubleshooting
Topic: Warning DC/DC converters with variable output
Replies: 12
Views: 745

Re: Warning DC/DC converters with variable output

I have used these converters successfully but never leaving the trimmer pot in place. The output voltage is (roughly) proportional to the pot resistance which, if open circuit, rises to the input voltage (they are wired as a simple variable resistor). The trimmer pots are simply not stable enough to...
by cjketle
Mon Aug 31, 2020 4:36 pm
Forum: Other programming languages
Topic: Introduction to BBC BASIC
Replies: 782
Views: 110598

Re: Introduction to BBC BASIC

Looks like there may be a build problem with the current console version as it won't run on a pi0/pi1b - halts with 'illegal instruction'. OK in pi2/3. Is it intended to support the earlier processors?

Chris K
by cjketle
Sat Aug 29, 2020 8:50 pm
Forum: Advanced users
Topic: Maximum Current Output from 3.3 V Pins - Pi Zero
Replies: 33
Views: 1427

Re: Maximum Current Output from 3.3 V Pins - Pi Zero

You need to specify a LDO (Low Drop Out) regulator. There are a lot of low cost modules around based on some variant of the AMS1117 which needs >4.75v for 3.3v out. Other devices are available...

Chris K
by cjketle
Sat Aug 29, 2020 5:00 pm
Forum: Advanced users
Topic: Maximum Current Output from 3.3 V Pins - Pi Zero
Replies: 33
Views: 1427

Re: Maximum Current Output from 3.3 V Pins - Pi Zero

If you are worried about a clean 3.3v and are already using a buck converter for the 12-5v transition the best solution is probably a linear 3.3v regulator from the 5v rail. This will be 66% efficient and only dissipate under .5w at 200ma.

Chris K
by cjketle
Sat Aug 01, 2020 11:23 am
Forum: Networking and servers
Topic: Pi WiFi with ESP8266?
Replies: 23
Views: 1279

Re: Pi WiFi with ESP8266?

There is firmware out there to do just this using a SLIP connection over the serial interface. See https://github.com/martin-ger/esp_slip_router. Obviously very slow (115Kb), but I can confirm that it does work. You will need the kit to flash the ESP depending on the module you use but it is straigh...
by cjketle
Sun Jul 05, 2020 11:05 am
Forum: General discussion
Topic: Want to create a VPN
Replies: 5
Views: 240

Re: Want to create a VPN

It rather depends on what else you want it to do and how much you are expecting of the VPN. I have an original 2012 era 256MB Pi1 occupying its sunset years as a Wireguard server to support access to my home network from outside. It seems up to undemanding use - for instance it can manage to stream ...
by cjketle
Fri Jun 26, 2020 3:06 pm
Forum: Networking and servers
Topic: Setup as router for use in third world countries?
Replies: 8
Views: 658

Re: Setup as router for use in third world countries?

Before you get too deep into what the right equipment fit is, you need to think about some other issues first. You first need to check out what ISP options are open to you. You are looking for a routed connection to the internet supplied by some third party provider so check out the costs and possib...
by cjketle
Wed Apr 29, 2020 11:03 am
Forum: Camera board
Topic: How to cut out visible light spectrum from IR camera
Replies: 5
Views: 754

Re: How to cut out visible light spectrum from IR camera

If you can source any (eg from scrap equipment), the dark red plastic shielding IR remote control receivers works well. Attached some examples from a NOIR camera and two different material samples, one of which is opaque to the naked eye, and the other a very dark red. BTW, the tree is green with wh...
by cjketle
Wed Mar 25, 2020 3:43 pm
Forum: General discussion
Topic: Real VT100 on Serial Port / Garbled Text on Buster
Replies: 20
Views: 1081

Re: Real VT100 on Serial Port / Garbled Text on Buster

I would look at your flow control settings first. The VT100 is a relatively slow device and is therefore rate limited - possibly to less than the selected baud rate can support - and particularly if you have smooth scrolling engaged. DEC typically used Xon/Xoff flow control rather than the hardware ...
by cjketle
Thu Dec 26, 2019 7:43 pm
Forum: Beginners
Topic: Can RP read punched paper tape from 1969 somehow?
Replies: 21
Views: 1597

Re: Can RP read punched paper tape from 1969 somehow?

Cant really do that now. I'm in the UK anyway. What you do not have is a simple textual document on tape, it will require more context to understand it. What you appear to have is a small piece of Lab software from 1969 that runs on a minimal Series 16 system (4/8Kw?) probably connected to a special...
by cjketle
Tue Dec 24, 2019 5:17 pm
Forum: Beginners
Topic: Can RP read punched paper tape from 1969 somehow?
Replies: 21
Views: 1597

Re: Can RP read punched paper tape from 1969 somehow?

OK, a bit more supposition. It looks like you have what was called a 'Self Loading System Tape' that loads a program into address '1000, the usual start address. 60 feet of tape will be about 30 x 12 x 10, about 3.5K words. In other words a 3K ish word program - ie not really enough to do very much....
by cjketle
Tue Dec 24, 2019 4:57 pm
Forum: Beginners
Topic: Can RP read punched paper tape from 1969 somehow?
Replies: 21
Views: 1597

Re: Can RP read punched paper tape from 1969 somehow?

That looks very like Honeywell series 16 tapes (see https://en.wikipedia.org/wiki/Honeywell_316). IIRC (and it was a *long* time ago) medic was a debugger program and the tape illustration looks like the '5-5-6' binary format used to punch out on an ASR33 without printing anything. If you are lookin...
by cjketle
Sat Nov 09, 2019 2:38 pm
Forum: Other projects
Topic: Messure AC current
Replies: 5
Views: 989

Re: Messure AC current

Bear in mind that will only tell you the current, not the power as the power factor is likely to be somewhat less than unity. If you are happy with the process of re-flashing the firmware you might be better with a Sonoff POW (https://www.banggood.com/search/1279097.html or other places)) flashed wi...
by cjketle
Sun May 12, 2019 3:46 pm
Forum: Troubleshooting
Topic: Rasberry Pi Don't Starts After Abrupt Shutdown due to short between 3V3 and 5V
Replies: 9
Views: 709

Re: Rasberry Pi Don't Starts After Abrupt Shutdown due to short between 3V3 and 5V

If you have any of those two pin jumpers that are/were often used to configure devices they can usefully be used to reduce the risk of this sort of mishap when probing around. If you always keep one covering the two 5v pins where they would be otherwise exposed then it is more difficult to contact t...
by cjketle
Mon Jan 14, 2019 7:54 pm
Forum: Advanced users
Topic: Raspberry PI cold boot attack protected / Zero out RAM after boot?
Replies: 71
Views: 8733

Re: Raspberry PI cold boot attack protected / Zero out RAM after boot?

For interest, I’ve carried out a few rough and ready experimental measurements on an early Pi1B to get an idea of the scale of the problem. This is done by writing a pattern into a fixed area of memory, powering off and on and reading the memory back to get an idea of how much has changed. These res...

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