A power and ground backplane to simplify IoT component connectivity

IoT projects are fun until you move them off the breadboard and then have to solder create reliable connections and power and ground connections.  Some people solder some people use small super-cheap breadboards. I tend to use jumper wires and connectors because most of my stuff is a one-off or super-small batch. It makes rework easy and reliable. The downside is that connectors take up space. The rest of this demonstrates a simple way of making this happen.

Video 

Schematic

Three sets of headers are soldered to a breadboard and joined to each other jin banks.

Power (5V) is injected at the jack.  There are power and ground connectors for each device that requires power or ground.

Power (5V) and ground lines run from each device and from the jack to the distribution connectors which are plugged into the headers.

3.3 Volt is not on the jack. It is supplied from a voltage regulator on the board and available on its own header row. It is supplied in the schematic from a voltage regulator on board the CPU/MCU and not from the external power jack or USB

Tie everything back to the same source

Connections should be as direct as possible.  Don't create loops. Don't route ground through a device to a different pin to another device.












Power Distribution

Bring all power and ground connections to a single point if possible. 

Sometimes I twist them all together wire-tie style and solder that bundle. The bundle doesn't take up a lot of space and provides a reliable connection. Then I'll shrink-wrap the solder point to avoid shorts

Here I built a power distribution hub.


 

All the single power and ground lines are point-to-point with only one pin-to-pin cable. Power and Ground run from the central location to every device.  I like to chain all of the components directly back to the same ground point.  This means there is always an N-Way connection to all N devices for both power and ground. 

Another approach is to make small power and ground connector banks out of protoboard and connector pins.  The picture at the right has 3 banks intended for ground, 3.3V, and 5V.  The connector on the right is bigger than the connecter set because I knew I'd have to add another later by adding another pin.

All the right-angle pins were soldered to the protoboard on the copper side.  Then I ran a bare wire across all the pins in a bank and soldered the wire to the pins.

Concerns

  • Connectors take up a lot more space than direct wire soldering.
  • The back of the protoboard should be covered in an insulator type of tape.

Revision History

Created 2023 02 21

Comments

Post a Comment

Popular posts from this blog

Understanding your WSL2 RAM and swap - Changing the default 50%-25%

Image
The Windows Subsystem for Linux operates as a virtual machine that can dynamically grow the amount of RAM to a maximum set at startup time.  Microsoft sets a default maximum RAM available to 50% of the physical memory and a swap-space that is 1/4 of the maximum WSL RAM.  You can scale those numbers up or down to allocate more or less RAM to the Linux instance. The first drawing shows the default WSL memory and swap space sizing. The images below show a developer machine that is running a dev environment in WSL2 and Docker Desktop.  Docker Desktop has two of its own WSL modules that need to be accounted for.  You can see that the memory would actually be oversubscribed, 3 x 50% if every VM used its maximum memory.  The actual amount of memory used is significantly smaller allowing every piece to fit. Click to Enlarge The second drawing shows the memory allocation on my 64GB laptop. WSL Linux defaults to a maximum RAM size of 5
Read more

Installing the RNDIS driver on Windows 11 to use USB Raspberry Pi as network attached

Image
I do a lot of my development and configuration via ssh into my Raspberry Pi Zero over the RNDIS connection. Some models of the Raspberry PIs can be configured with  gadget drivers  that let the Raspberry pi emulate different devices when plugged into computers via USB. My favorite gadget  is the network profile that makes a Raspberry Pi look like an RNDIS-attached network device.  All types of network services travel over an RNDIS device without knowing it is a USB hardware connection. A Raspberry Pi shows up as a Remote NDIS (RNDIS) device when you plug the Pi into a PC or Mac via a USB cable. The gadget  in the Windows Device Manager picture shows this RNDIS Gadget connectivity between a Windows machine and a Raspberry Pi. The Problem Windows 11 and Windows 10 no longer auto-installs the RNDIS driver that makes magic happen. Windows recognizes that the Raspberry Pi is some type of generic USB COM device. Manually running W indows Update  or  Update Driver  does  not  install the RNDI
Read more

DNS for Azure Point to Site (P2S) VPN - getting the internal IPs

Image
I wanted to access all my Azure resources without making any of them visible to the Internet.   The easiest give my local machine access to everything on my Azure Virtual Network (VNET) was to connect to it over VPN. It turns out creating Azure VPN gateways and connecting to Azure VPN endpoints is easy.  There are some subtleties in getting DNS name resolution to work that can confuse when first starting out. Setting the Stage There are a few ways to get to Azure endpoints and resources that are blocked from the internet.  We can  Create a Point-to-Site connection from our local machines to Azure Network Gateways Create a Site-to-Site network connection from our local networks to Azure Network Gateways. Use Bastion Hosts Use Cloud Shell Leave everything open to the internet. I chose a Point-to-Site (P2S) VPN connection that connects from my laptop to a VNet Gateway.  That joins my laptop
Read more