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The Cabin >> Raspberry and Other Pies >> Death of a Raspberry Pi Zero
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Message started by Fernando on Aug 7^th, 2019, 8:23pm

Title: Death of a Raspberry Pi Zero
Post by Fernando on Aug 7^th, 2019, 8:23pm

Not since the early days of the Raspberry Pi have we seen many R-Pies being “killed” from improper wiring and sending power to through the GPIO to run the Raspberry Pi. Sending power through the 5V and 3.3V lines of the GPIO can run the unit, but if there is a short circuit or over voltage condition, it will damage the Raspberry Pi. This is because the power being put in is not being filtered out by the unit’s power supply section that is entered through the Micro USB Port.

The Raspberry Pi Zero has been around for over 3 years (at the time of this writing), and it has been a “Godsend” in terms of a small system that can be placed into various applications with minimal need for additional space and power requirements. You can put down 3 Raspberry Pi Zeros together along their short side and it would be the same size as Raspberry Pi Model A+, 4 Raspberry Pi Zeros and it would be the same size as a Raspberry Pi Model B+ Series (which includes the Model 2, Model 3, Model 3+ and Model 4). Since before the Raspberry Pi Zero, Makers and DYI’ers have been caution in wiring up their units to various projects to protect them from improper voltage input through the GPIO. And such caution has been used when working with the Raspberry Pi Zero.

But there have been a couple of kits which circumvents power input from the Micro USB Port and sends power through the GPIO to run the Raspberry Pi. There also has been a few careless Makers and DIY’ers who have powered the Raspberry Pi Zero through the USB Port. It is in these cases which the Raspberry Pi unit has been rendered useless.

Unlike all the other models of the Raspberry PI since the first 256MB Model Bs of 2011, all Raspberry Pi Models have a voltage regulation circuitry that converts the 5V coming in from the Micro USB Port to 5V, 3.3V and 2.5V. On later models from the Model B+ and A+, the regulation circuit is a switching power supply, which uses less power than Linear Voltage Regulators used before. These power regulation circuits take up a large area of the board. None of this exists on the Raspberry Pi Zero series. From what I can see, there is a tiny IC for possibly pulsing the power to make it a switching supply and several resistors to step down the 5V from the micro USB Port to 3.3V and 2.5V as needed by the R-Pi’s circuit chips. There are no regulator IC to steady the voltage on the R-Pi 0 and from their size, it looks like it can be overwhelmed with a slight overvoltage. Thus the problem.

When putting in power through the GPIO, that power has to be spot on dead still level. If there is any input voltage fluctuation, it will affect the operation of the RPi 0. If there is an overvoltage on the GPIO, it will totally effect the R-Pi 0 with immediate and everlasting damage to the unit.

What gets to me is the attitude some people have, including those on the Raspberry Foundation itself have. “It’s a $5 computer board, why not buy another one?” This is not always an option for some. Travel, costs, and availability are factors that make a $5 into a $25 computer and out of reach for a someone to just accidentally killed their board. In thinking this is an extreme, but what about the other R-Pi Units? How much would it cost to repair them? I have repaired and resurrected dead R-Pi units (the older Model Bs) by replacing their voltage regulators for less than $5 in obtaining the replacement regulators. Micro-soldering with standard soldering tools was a female rabid dog but I got it done. But I diagnosed a couple other dead systems and have concluded that their CPU/GPU/I/O chip is at fault, replace it and one can bring back a dead R-Pi unit. From what I can tell this is what needs to be done with dead R-Pi 0 units. Repairing dead R-Pi units, this would eliminate a lot of e-waste.

In the past, the battle cry was “Never power the Raspberry Pi through its GPIO!” It should be held true to this day but it is not. Today one has to be vigilant in their wiring and power connecting of their R-Pi units in their projects. One has to take caution and review of their power supplies if they intend to power the R-Pi through the GPIO. The correct way to connect an R-Pi to a project is to power it through its Micro USB port and ground what connecting boards to the ground pins of the GPIO, and DO NOT CONNECT power into the GPIO though you can use the power from the GPIO to power the connecting boards.

Also, the Logic Voltage from the R-Pi is 3.3v, when most boards use a 5v TTL logic input/output. One needs to add an adapter circuit to convert 5v TTL Logic to Lower Power 3.3v Logic Levels. This is not too hard to do, though it can be tricky in if you connect an Arduino board which uses 5v TTL Logic to the R-Pi 3.3v Logic pins. There are ways to do it and most online instructions tell you how to do it, so do not take shortcuts.