dln2 — Unified DLN2 USB I/O Board Wrapper

Drop-in replacement for the four independent dln2_*_wrapper packages.
All modules share a single USB connection — no echo-counter conflicts, no USB contention.

Originally developed for the Pico USB I/O Board.

Installation

pip install git+https://github.com/syabyr/dln2_wrapper

Requires: pyusb

Quick Start

from dln2 import Dln2Connection, SpiDev, GPIO, SMBus, ADC

conn = Dln2Connection()          # one USB connection

# ── SPI ─────────────────────────────────────────────────
spi = SpiDev(conn)
spi.mode = 3
spi.max_speed_hz = 16_000_000
rx = spi.xfer2([0x9F, 0x00, 0x00, 0x00])  # JEDEC ID

# ── GPIO ────────────────────────────────────────────────
gpio = GPIO(conn)
gpio.enable_pin(25)
gpio.set_direction(25, "out")
gpio.write(25, 1)                 # set pin HIGH
val = gpio.read(25)               # read pin level

# ── I2C ─────────────────────────────────────────────────
i2c = SMBus(conn)
i2c.open()
devices = []
for addr in range(1, 128):
    try:
        i2c.write_byte(addr, 0)
        devices.append(addr)
    except: pass

# ── ADC ─────────────────────────────────────────────────
adc = ADC(conn, vref=3.3)
volts = adc.read_volts(0)         # read channel 0 voltage

conn.close()

Multi-Device Support

from dln2 import list_devices, Dln2Connection

for d in list_devices():
    print(f"[{d.index}] serial={d.serial}")

lcd_conn = Dln2Connection(index=0)     # first board — ST7789 display
nfc_conn = Dln2Connection(index=1)     # second board — NFC reader
# or by exact serial:
# conn = Dln2Connection(serial="4250304B38353817")

Module API

SpiDev

spidev-compatible API: xfer(), xfer2(), writebytes(), readbytes(),
mode, max_speed_hz, bits_per_word, cshigh, lsbfirst, host_hold_cs

GPIO

set_direction(pin, "in"|"out"), write(pin, value), read(pin),
toggle(pin), get_direction(pin), set_event(pin, type), poll_event()

SMBus

smbus-compatible API: write_byte(), read_byte_data(),
write_word_data(), read_word_data(), read_block_data(),
write_block_data(), write_i2c_block_data(), read_i2c_block_data()

ADC

read_channel(channel), read_all(), read_volts(channel),
set_resolution(bits), enable_channel(ch), disable_channel(ch)

CLI Commands

After installation, the following commands are available:

# GPIO
dln2-gpio-info --pin 2
dln2-gpio-toggle --pin 25 --count 5 --interval 0.2
dln2-gpio-watch --pin 2 --timeout-ms 500

# ADC
dln2-adc-info
dln2-adc-watch --channel 0 --interval 0.5

# I2C
dln2-i2c-scan
dln2-i2c-test --address 0x76 --register 0xD0 --read 1

# SPI
dln2-spi-test
dln2-bpw-test

Examples

Core examples (this repo)

Basic I/O operations that exercise the wrapper itself:

# SPI JEDEC ID read
python3 examples/spidev_test.py

# SPI bits-per-word cycle
python3 examples/bpw_tester.py

# GPIO pin toggle (default: Pico LED)
python3 examples/gpio_toggle.py --pin 25

# GPIO pin info
python3 examples/gpio_info.py --pin 2

# GPIO event watch
python3 examples/gpio_watch.py --pin 2

# I2C bus scan
python3 examples/i2c_scan.py

# I2C register read/write
python3 examples/i2c_test.py --address 0x76 --register 0xD0 --read 1

# ADC read
python3 examples/adc_info.py

# ADC stream
python3 examples/adc_watch.py --channel 0

Device-specific examples (separate repo)

Sensor test scripts live in dln2_examples:

git clone https://github.com/syabyr/dln2_examples
cd dln2_examples/i2c

python3 bh1750_full_test.py      # BH1750  ambient light    @ 0x23
python3 bme280_full_test.py      # BME280  temp/press/humid @ 0x76
python3 bmp180_full_test.py      # BMP180  temp/pressure    @ 0x77
python3 tsl2561_full_test.py     # TSL2561 ambient light    @ 0x39
python3 mpu9250_full_test.py     # MPU9250 9-axis IMU       @ 0x68

Why Unified?

Pin Constraints

Firmware Compatibility

To flash updated firmware:

1. Hold the BOOTSEL button while connecting the Pico (or press and release RESET while holding BOOTSEL)
2. Copy dln2.uf2 to the RPI-RP2 USB drive that appears
3. The Pico reboots automatically with the new firmware

Related

• pico-usb-io-board — RP2040 firmware
• dln2_examples — sensor test scripts (BH1750, BME280, BMP180, TSL2561, MPU9250, …)

License

MIT