SNTP

Connect to WiFi and synchronize the device clock via NTPNetwork Time Protocol, so new Date() returns real wall-clock time. Uses the wifi and sntp APIs.

Hardware

• Any ESP32 board with WiFi
• USBUniversal Serial Bus cable
• A WiFi network with internet access

Setup

Set your WiFi credentials as environment variables:

pnpm

pnpm mikro env set WIFI_SSID YourNetworkName --no-secret
pnpm mikro env set WIFI_PASSPHRASE

npm

npx mikro env set WIFI_SSID YourNetworkName --no-secret
npx mikro env set WIFI_PASSPHRASE

yarn

yarn mikro env set WIFI_SSID YourNetworkName --no-secret
yarn mikro env set WIFI_PASSPHRASE

bun

bunx mikro env set WIFI_SSID YourNetworkName --no-secret
bunx mikro env set WIFI_PASSPHRASE

Code

import {env} from 'mikro/env'
import {sleep} from 'mikro/sleep'
import {sntp} from 'mikro/sntp'
import {wifi} from 'mikro/wifi'

await sleep(2000)
console.log('Current time at startup: %s', new Date())

const ssid = env.require('WIFI_SSID')
const passphrase = env.require('WIFI_PASSPHRASE')

// Connect to WiFi
console.log(`Connecting to ${ssid}...`)
const connectResult = await wifi.connect({ssid, passphrase})
if (!connectResult.ok) {
  console.error('WiFi connect failed:', connectResult.error)
} else {
  console.log('Connected! IP: %s', connectResult.value.ip)

  // One-shot time sync
  console.log('Syncing time...')
  const syncResult = await sntp.sync({timezone: 'CET-1CEST,M3.5.0,M10.5.0/3'})
  if (!syncResult.ok) {
    console.error('SNTP sync failed:', syncResult.error)
  } else {
    console.log('Time synced: %s', syncResult.value.time)
    console.log('Current time: %s', new Date())
  }
}

Walkthrough

1. Before sync. new Date() returns a timestamp near epoch 0 at startup, since the ESP32 has no battery-backed clock. The initial log shows this.

2. WiFi first. Time sync requires an internet connection. The example connects to WiFi and checks the result before attempting SNTPSimple Network Time Protocol.

3. Timezone string. The timezone option uses POSIXPortable Operating System Interface TZ format. CET-1CEST,M3.5.0,M10.5.0/3 means Central European Time (UTCCoordinated Universal Time+1), with daylight saving (CESTCentral European Summer Time) starting the last Sunday of March and ending the last Sunday of October.

4. One-shot vs. background. sntp.sync() does a single time sync by default. Pass {background: true} to keep re-syncing periodically. The returned object includes a stop() function to cancel background sync.

Create project

pnpm

pnpm create mikro --template sntp

npm

npm create mikro -- --template sntp

yarn

yarn create mikro --template sntp

bun

bun create mikro --template sntp

Run it

pnpm

pnpm install
pnpm mikro flash  # only needed once per board
pnpm mikro dev

npm

npm install
npx mikro flash  # only needed once per board
npx mikro dev

yarn

yarn install
yarn mikro flash  # only needed once per board
yarn mikro dev

bun

bun install
bunx mikro flash  # only needed once per board
bunx mikro dev

The time jumps from near-epoch to the correct wall-clock time after the sync completes.

View source on GitHub