BITCOIN · SHA256D

Mining Bitcoin on ARM

1 · Should you mine this on a CPU?

No — and we'll say it plainly: SHA256d on a CPU earns effectively zero against ASICs. So why include it? Because people pay real money for ESP32 lottery-miner gadgets that hash in the tens to hundreds of kilohashes — while an old phone from a drawer does ~90 MH/s on the same few watts: roughly a thousand ESP32s' worth of solo-lottery tickets, from hardware you already own. It's also a clean benchmark of this miner's SHA2 hardware-crypto path, and handy for testing. If you want a serious lottery, USB ASICs in the terahash class exist; if you want CPU revenue, mine Verus or Monero.

2 · The solo-lottery angle

Solo pools (e.g. public-pool.io) let any device attempt whole blocks: no shared payouts — you win nothing, or the full block reward if your device finds a block. At CPU hashrates the odds are astronomically against you (think lifetimes, not years). Some people enjoy holding the ticket anyway; that's the honest pitch, in full.

3 · Get a wallet

Any Bitcoin wallet address works — Sparrow, Electrum, or a hardware wallet. For lottery mining, use an address whose keys you control: if lightning ever strikes, you want the reward in your own wallet, not an exchange's.

4 · Configure the miner

CLI

command

$ ./primo -a sha256d -o stratum+tcp://public-pool.io:3333 \
      -u YOUR_BTC_ADDRESS.worker1 -p x

config.json

config.json — run with ./primo -c config.json

{
  "algo": "sha256d",
  "url":  "stratum+tcp://public-pool.io:3333",
  "user": "YOUR_BTC_ADDRESS.worker1",
  "pass": "x"
}

APK

Configuration → Algorithm → sha256d. Threads defaults to your core count.
Primary pool: URL as above, wallet/user = your BTC address + .workername, password x.
SAVE, then START MINING. The dashboard shows accepted shares within a minute.

APK configuration with sha256d algorithm and public-pool.io — The sha256d profile in the app.

APK dashboard mining SHA256d at 76.32 MH/s — Mining SHA256d at 76 MH/s.

5 · What to expect

Hardware	Hashrate
A76-class big core (1 thread)	~16 MH/s
8-core phone or RK3588 board	~90 MH/s

For scale: a modern Bitcoin ASIC does ~200 TH/s — about 2,000,000× an 8-core phone.

6 · SHA256d-specific notes

The ~90 MH/s figure comes from the ARMv8 SHA2 hardware-crypto instructions — it's a good quick check that your SoC's crypto extensions are being used.
./primo -a sha256d --benchmark benchmarks without connecting to any pool.
On a conventional (shared-payout) SHA256d pool your earnings will round to zero — most have payout minimums a CPU never reaches.
Dev fee on SHA256d: 1% (60 s per 100 min), logged in the console.

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