KEYESTUDIO 5V DCAC 4-Channel Relay Hat Shield Module Expansion Board for Raspberry Pi 4/A+/B+/Pi 2 Model B/Pi 3 Model B

It fits my Raspberry Pi 4B snugly and works as expected. I installed python3-rpi.gpio and it is easy from there on. The 4 relays are on 'pins' 4,22,6,26 in BCM mode and on 7,15,31,37 in BOARD mode. This is not well documented and I needed to do some digging. Am attaching a screenshot of the python program I used to test it - just cycles across them and you'll hear the click and see the led.

Pros: * price is decent * function seems to work as advertised. Documentation is only helpful if you use WiringPi. Cons: * pin header is not a pass-thru. I ended up adding another pass-thru header underneath for some spacing, and added longer threaded standoffs to compensate. * PCB traces for relay contacts are exposed on PCB bottom; this is not very safe if you plan to use the board to control line (120V AC) voltages!! I added a layer of Kapton tape to the underside to prevent accidental shorting and "letting the smoke out". * Relay J2 uses GPIO 4, which conflicts with the default 1-wire function on RPi. It would be nice if there was some configurability with jumpers etc. Also would be nice if this was mentioned in the documentation wiki Overall I am happy enough with these boards. It would be nice if the vendor would include a schematic in the documentation, but I understand this gives away the simple design.

I gave it a rating of 5 on "easy to use", but, only because I'm passing familiarity with python. To somebody who doesn't, it might present a slight challenge. I honestly only needed a single relay, but I went with this one anyway cuz it's mounted inside a robot, which I might end up finding a use for the other 3 relays anyway Bottom line, it functions, it's fine, I'd buy it again if I needed to

I have used other 4 channel relays with my raspberry pi before but none that mounted directly to the pi. This format eliminates jumper wires from your pi to your relay board. I like that the board comes with spacers, nuts, and bolts to secure it to the pi and protect the gpio pins on the pi from unnecessary pressure or tweaks. As stated by a previous reviewer my only complaint is that you don't have access to the unused gpio pins on the pi board (although you could connect to the exposed solder points on the relay board).

I wanted a way to control some heating elements and fans from a Raspberry Pi in order to circulate warm air around my 3D printer. This board was just the ticket. It's mostly well thought out and has many good design features. Pros: - 5V operation is convenient because it matches the Raspberry Pi itself. - Compact layout fits neatly in the airspace above the Raspberry Pi. - Relays are very capable. Many competitors have much lower contact current ratings. - LED indicators are a nice touch. - Actually mates to the GPIO header, rather than relying on jumper wires like most of the competing products with the same power handling capability. Cons: - The screw block doesn't work well on stranded wire. It's clearly designed for use with solid wire or stranded wire that's been terminated with pins or ferrules. I'd love it if the block were more wire-agnostic. Such parts do exist. - Inconsistent and incorrect documentation on the web regarding which IOs connect to which relay. I had to just try all of them to figure it out. Maybe there are multiple hardware revisions floating around? - They shouldn't bother providing the mounting hardware. The screws are very low quality (very soft) and somewhat too long. Nuts are a weird choice - better to use a case with threaded inserts. - I had to add flyback diodes across the control coils to prevent rebooting the Raspberry Pi when de-energizing the relays. - No great way (e.g., resistors to move around, jumpers, DIP switches) to remap IOs in case of collision. I ended up just disconnecting the first channel to avoid a collision with GPIO 4. And I have a feature request. It would be lovely if there were some optional diodes to force channels when other channels are on. I ended up adding a diode between two channels myself in order to force the fan to be on whenever the heater was on as a safety measure. I recognize that's a bit esoteric and unlikely to be implemented in future revisions. All-in-all, I'm quite happy with this purchase. But if I needed another board to do something similar, I'd probably design one myself.

I wanted to leave a review here because I have read a number of reviews which stated dissatisfaction at the level of documentation. It is, indeed, true that the box doesn't have any documentation, only the relay module. However, I saw a QR code on the back of the box, so I scanned it and opened the web site to which it pointed. This gave me not only all of the documentation I could possibly want, but also provided sample code and links to places where I could download more! I simply used the basic, sample, code on the site, and (after installing the "wiredPi" library), it compiled and worked first time! My project is currently working fine with this relay. I would definitely order it again when/if I need another 4 relay module.

As other reviewers have mentioned, this unit does have a few flaws: 1. The stand-offs are about 1mm too short, leaving a gap between the HAT and the top of the stand-off, so don't torque the screws down too far. I happened to have some tiny plastic washers on hand that made everything line up perfectly, so I lucked out. 2. The mounting screws are very close to the terminals on the first and last relay, so make sure you mind how far you strip your wires, and don't use wires that are too large. Better yet, I'd recommend using nylon stand-offs/screws instead of the metal ones included. 3. The documentation can be hard to find, and when you do, I can see how it could be very confusing for beginners. Here's the full pinout: Relay #1: - BCM pin 4 - WiringPi pin 7 - Physical pin 7 Relay #2: - BCM pin 22 - WiringPi pin 3 - Physical pin 15 Relay #3: - BCM pin 6 - WiringPi pin 22 - Physical pin 31 Relay #4: - BCM pin 26 - WiringPi pin 25 - Physical pin 37 In Linux, if you're looking at the raw pins in /sys/class/gpio, you'll want to use the BCM pin numbers (e.g. Relay #1 would be /sys/class/gpio/gpio4).

As others have mentioned the following GPIO to relay map worked perfectly for me: gpio 4 is relay 1 gpio 22 is relay 2 gpio 6 is relay 3 gpio 26 is relay 4 Also others have mentioned that the relay controller mounting hardware doesn't quite fit the board (leaves small gaps, see attached pictures) but it does still work. The other thing I will mention is that you need to be cognizant of the height of the heat sink you have on the PI processor. If the heatsink is too tall it will prevent the relay controller from being mounted correctly and possibly damage the hardware if the heatsink and relay controller touch. I learned the hard way.

Installé sur le raspberry raccordé à une imprimante 3D (octoprint) j'obtiens bien les ouvertures et fermetures. Pour infos, dans l'ordre les GPIO 4, 22, 6 et 26 corresponde au relais 1, 2, 3 et 4. Le produit étant fournie sans notice, c'est bon à savoir. La puissance des relais permet du 10A sous 220V.

I am posting this review after my initial test since I won't be able to use it for some time. The board works great and easy to setup. I control it with python using code that I created for the Raspberry Pi Gertboard. I think the posted online manual is not accurate in terms of the GPIOs that are used (at least in my case), but that is not a problem. I used my multimeter and figured it out. In case it might help someone, here is what I found: GPIO4 is Relay 1 GPIO22 is Relay 2 GPIO6 is Relay 3 GPIO26 is Relay 4 One thing to note is that I couldn't use it with any of my Pi cases. I can only use the base of the case (see the pictures), but that's not an issue.

Excellent

Fa il suo lavoro egregiamente

KEYESTUDIOのサイトにあるサンプルでは、WiringPiライブラリを使用しているが、ただのGPIOなので、/sys/class/gpioでも、もちろん使える。 但し、この場合のピン番号は、Raspberry Piの40ピンヘッダの1番ピン側から、GPIO4、GPIO22、GPIO6、GPIO26となる。 出力をHighにすると、該当するリレー付近の赤いLEDが光る。 とりあえず、普通に使えており、星は5つでも良かったが、製品の説明には、「インストールパッケージ、ソースコードおよびクイックスタートガイドPDFを提供します」とあるが、M2.5ネジ、ナット、スペーサー以外は何も入っておらず、KEYESTUDIOのサイトから入手することになる。その際の型番はKS0212となる。 あと、1点注意が必要なのは、基板を固定する四隅のネジ穴のうち、リレー出力側のネジ穴が、両端のターミナルの穴を塞ぐ位置にあるので、ネジが突出する長さによっては、非常に邪魔になるどころか、その穴にケーブルが挿せなくなるのがダメ。よって、星は-1。