added support for EP0099

[cadusk]

EP0099 is a stackable 4-channel relay hat that communicates with platforms via i2c interface.

Manufacturer: 52pi Wiki page: https://wiki.52pi.com/index.php/DockerPi_4_Channel_Relay_SKU:_EP-0099

[googlebot]

Thanks for your pull request. It looks like this may be your first contribution to a Google open source project (if not, look below for help). Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

:memo: Please visit https://cla.developers.google.com/ to sign.

Once you've signed (or fixed any issues), please reply here with @googlebot I signed it! and we'll verify it.

---

What to do if you already signed the CLA

Individual signers

• It's possible we don't have your GitHub username or you're using a different email address on your commit. Check your existing CLA data and verify that your email is set on your git commits.

Corporate signers

• Your company has a Point of Contact who decides which employees are authorized to participate. Ask your POC to be added to the group of authorized contributors. If you don't know who your Point of Contact is, direct the Google project maintainer to go/cla#troubleshoot (Public version).
• The email used to register you as an authorized contributor must be the email used for the Git commit. Check your existing CLA data and verify that your email is set on your git commits.
• The email used to register you as an authorized contributor must also be attached to your GitHub account.

ℹ️ Googlers: Go here for more info.

[codecov-io]

Codecov Report

Merging #5 (ccc1c29) into main (296894b) will increase coverage by 0.1%. The diff coverage is 82.9%.

@@           Coverage Diff           @@
##            main      #5     +/-   ##
=======================================
+ Coverage   63.2%   63.3%   +0.1%     
=======================================
  Files         46      47      +1     
  Lines       4034    4069     +35     
=======================================
+ Hits        2549    2574     +25     
- Misses      1357    1364      +7     
- Partials     128     131      +3     

Impacted Files	Coverage Δ
ep0099/ep0099.go	82.9% <82.9%> (ø)
lepton/lepton.go	85.7% <0.0%> (-1.4%)	:arrow_down:
as7262/as7262.go	98.0% <0.0%> (-1.0%)	:arrow_down:

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 296894b...ccc1c29. Read the comment docs.

[cadusk]

I like this approach, I just don't see how to figure out which channel we're referring to in method Out since we're passing the index to the array, not to dev.

type (r *Relay) Out(l gpio.Level) error {
    _, err := d.i2c.Write([]byte{channel, byte(StateOn)})
    r.state = StateOn
    return err
}

I've been learning a lot with this PR, maybe there's a way to figure out what channel would be without looping through Relays and comparing d to items in the array.

Maybe this solution needs some more thinking. I am happy with the results so far and am ok with merging it like this.

[maruel]

One last point: do you mind following the instruction at https://github.com/periph/devices/pull/5#issuecomment-775185342?

[maruel]

gohci

[maruel]

Thanks!