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James Lewis

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A Vintage Computing Adventure (Mega IIe)

https://www.baldengineer.com/wp-content/uploads/2024/03/Circuit-Break-Audiogram-420.mp4

Parker and Stephen invited me back to discuss the Mega IIe project on the MacroFab Circuit Break podcast. This discussion was far more casual than my past appearances. It was the first time I didn’t feel the need to do any prep work for their excellent questions!

We talked through the overall experience of rev 1, rev 2, and rev 3. I appreciated the chance to talk about my motivations behind the Mega IIe project, why I like the Apple II platform so much, and getting to nerd out with Parker on analog video signal concepts.

Circuit Break Podcast #420

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KiCad

Eight KiCad 8 features I like

KiCad 8 just dropped. Here’s an AddOhms video covering eight must-try features! The February 2024 release brings a whole host of new stuff to the Schematic editor. However, the PCB editor, CLI, and Simulation tools also received attention. (There are something like 900 closed issues for the 8.0.0 Milestone!) Which of these is your favorite?

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Blog

Accessing USB instruments with pyvisa on Linux

USB-Based instruments that do not appear to the host as a virtual com port (VCP) usually use libusb for communication. The pyvisa-py driver for pyvisa can communicate with these instruments. However, you must first create a udev rule (and possibly a user group.)

If you see the device in lsusb, but not the pyvisa ResourceManager, you need to add (or modify a udev rule): 

# backup 99-com.rules (if it exists)
cp /etc/udev/rules.d/99-com.rules /etc/udev/rules.d/99-com.rules.BAK

# (create and) edit the file
nano /etc/udev/rules.d/99-com.rules

# Add the following line
SUBSYSTEM=="usb", MODE="0666", GROUP="usbusers"

# create a usbusers group
sudo groupadd usbusers

# add your account to the new group
sudo usermod -a -G usbusers USERNAME

# restart udev
/etc/init.d/udev restart
(Although, you are probably better off rebooting.)
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Workbench Wednesdays

nRF7002 DK vs EK vs EB Hands-On

In August 2022, Nordic Semiconductor announced its first Wi-Fi product. The nRF7002 is a dual-band (2.4 and 5 GHz) Wi-Fi 6 compatible companion IC. It does not have a general-purpose microcontroller built-in. Instead, Nordic intends for you to combine it with another microcontroller, like one of their nRF52 or nRF53-series system on chip (SoC).

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RP2040

RP2040 Debug and Turn-On Tips

During the component shortage, I got to know Raspberry Pi’s RP2040 microcontroller. It is a dual-core Arm Cortex-M0+ with about 262 kilobytes of RAM. The feature I like most is the programmable IO pins. These are small state machines that run independently of the Arm cores. They allow for some clever tricks. For example, I used them extensively on the Mega IIe project.

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