diff --git a/mpu9250/spi.go b/mpu9250/spi.go
deleted file mode 100644
index 59e2eb4..0000000
--- a/mpu9250/spi.go
+++ /dev/null
@@ -1,123 +0,0 @@
-// Copyright 2020 The Periph Authors. All rights reserved.
-// Use of this source code is governed under the Apache License, Version 2.0
-// that can be found in the LICENSE file.
-
-package mpu9250
-
-import (
-	"fmt"
-
-	"periph.io/x/conn/v3/gpio"
-	"periph.io/x/conn/v3/physic"
-	"periph.io/x/conn/v3/spi"
-	"periph.io/x/conn/v3/spi/spireg"
-)
-
-// DebugF the debug function type.
-type DebugF func(string, ...interface{})
-
-// SpiTransport Encapsulates the SPI transport parameters.
-type SpiTransport struct {
-	device spi.Conn
-	cs     gpio.PinOut
-	debug  DebugF
-}
-
-// NewSpiTransport Creates the SPI transport using the provided device path and chip select pin reference.
-func NewSpiTransport(path string, cs gpio.PinOut) (*SpiTransport, error) {
-	dev, err := spireg.Open(path)
-	if err != nil {
-		return nil, wrapf("can't open SPI %v", err)
-	}
-	conn, err := dev.Connect(1*physic.MegaHertz, spi.Mode0, 8)
-	if err != nil {
-		return nil, wrapf("can't initialize SPI %v", err)
-	}
-	return &SpiTransport{device: conn, cs: cs, debug: noop}, nil
-}
-
-// EnableDebug Sets the debugging output using the local print function.
-func (s *SpiTransport) EnableDebug(f DebugF) {
-	s.debug = f
-}
-
-func (s *SpiTransport) writeByte(address byte, value byte) error {
-	s.debug("write register %x value %x", address, value)
-	var (
-		buf = [...]byte{address, value}
-		res [2]byte
-	)
-	if err := s.cs.Out(gpio.Low); err != nil {
-		return err
-	}
-	if err := s.device.Tx(buf[:], res[:]); err != nil {
-		return err
-	}
-	return s.cs.Out(gpio.High)
-}
-
-func (s *SpiTransport) writeMagReg(address byte, value byte) error {
-	return s.writeByte(address, value)
-}
-
-func (s *SpiTransport) writeMaskedReg(address byte, mask byte, value byte) error {
-	s.debug("write masked %x, mask %x, value %x", address, mask, value)
-	maskedValue := mask & value
-	s.debug("masked value %x", maskedValue)
-	regVal, err := s.readByte(address)
-	if err != nil {
-		return err
-	}
-	s.debug("current register %x", regVal)
-	regVal = (regVal &^ maskedValue) | maskedValue
-	s.debug("new value %x", regVal)
-	return s.writeByte(address, regVal)
-}
-
-func (s *SpiTransport) readMaskedReg(address byte, mask byte) (byte, error) {
-	s.debug("read masked %x, mask %x", address, mask)
-	reg, err := s.readByte(address)
-	if err != nil {
-		return 0, err
-	}
-	s.debug("masked value %x", reg)
-	return reg & mask, nil
-}
-
-func (s *SpiTransport) readByte(address byte) (byte, error) {
-	s.debug("read register %x", address)
-	var (
-		buf = [...]byte{0x80 | address, 0}
-		res [2]byte
-	)
-	if err := s.cs.Out(gpio.Low); err != nil {
-		return 0, err
-	}
-	if err := s.device.Tx(buf[:], res[:]); err != nil {
-		return 0, err
-	}
-	s.debug("register content %x:%x", res[0], res[1])
-	if err := s.cs.Out(gpio.High); err != nil {
-		return 0, err
-	}
-	return res[1], nil
-}
-
-func (s *SpiTransport) readUint16(address ...byte) (uint16, error) {
-	if len(address) != 2 {
-		return 0, fmt.Errorf("only 2 bytes per read")
-	}
-	h, err := s.readByte(address[0])
-	if err != nil {
-		return 0, err
-	}
-	l, err := s.readByte(address[1])
-	if err != nil {
-		return 0, err
-	}
-	return uint16(h)<<8 | uint16(l), nil
-}
-
-func noop(string, ...interface{}) {}
-
-var _ Proto = &SpiTransport{}