diff --git a/frc971/imu_reader/imu.cc b/frc971/imu_reader/imu.cc
new file mode 100644
index 0000000..b477e4c
--- /dev/null
+++ b/frc971/imu_reader/imu.cc
@@ -0,0 +1,166 @@
+#include "frc971/imu_reader/imu.h"
+
+#include "aos/util/crc32.h"
+#include "glog/logging.h"
+
+namespace frc971::imu {
+
+namespace {
+
+constexpr size_t kReadSize = 50;
+constexpr double kGyroScale = 1 / 655360.0 / 360.0 * (2 * M_PI);
+constexpr double kAccelScale = 1 / 26756268.0 / 9.80665;
+constexpr double kTempScale = 0.1;
+
+}  // namespace
+
+Imu::Imu(aos::ShmEventLoop *event_loop, double encoder_scalar)
+    : event_loop_(event_loop),
+      imu_sender_(
+          event_loop_->MakeSender<frc971::IMUValuesBatch>("/localizer")),
+      encoder_scalar_(encoder_scalar) {
+  imu_fd_ = open("/dev/adis16505", O_RDONLY | O_NONBLOCK);
+  PCHECK(imu_fd_ != -1) << ": Failed to open SPI device for IMU.";
+  aos::internal::EPoll *epoll = event_loop_->epoll();
+  epoll->OnReadable(imu_fd_, [this]() {
+    uint8_t buf[kReadSize];
+    ssize_t read_len = read(imu_fd_, buf, kReadSize);
+    // TODO: Do we care about gracefully handling EAGAIN or anything else?
+    // This should only get called when there is data.
+    PCHECK(read_len != -1);
+    CHECK_EQ(read_len, static_cast<ssize_t>(kReadSize))
+        << ": Read incorrect number of bytes.";
+
+    auto sender = imu_sender_.MakeBuilder();
+
+    const flatbuffers::Offset<frc971::IMUValues> values_offset =
+        ProcessReading(sender.fbb(), absl::Span(buf, kReadSize));
+    const flatbuffers::Offset<
+        flatbuffers::Vector<flatbuffers::Offset<frc971::IMUValues>>>
+        readings_offset = sender.fbb()->CreateVector(&values_offset, 1);
+    frc971::IMUValuesBatch::Builder batch_builder =
+        sender.MakeBuilder<frc971::IMUValuesBatch>();
+    batch_builder.add_readings(readings_offset);
+    imu_sender_.CheckOk(sender.Send(batch_builder.Finish()));
+  });
+}
+
+flatbuffers::Offset<frc971::IMUValues> Imu::ProcessReading(
+    flatbuffers::FlatBufferBuilder *fbb, const absl::Span<uint8_t> message) {
+  absl::Span<const uint8_t> buf = message;
+
+  uint64_t driver_timestamp;
+  memcpy(&driver_timestamp, buf.data(), sizeof(driver_timestamp));
+  buf = buf.subspan(8);
+
+  uint16_t diag_stat;
+  memcpy(&diag_stat, buf.data(), sizeof(diag_stat));
+  buf = buf.subspan(2);
+
+  double x_gyro = ConvertValue32(buf, kGyroScale);
+  buf = buf.subspan(4);
+  double y_gyro = ConvertValue32(buf, kGyroScale);
+  buf = buf.subspan(4);
+  double z_gyro = ConvertValue32(buf, kGyroScale);
+  buf = buf.subspan(4);
+  double x_accel = ConvertValue32(buf, kAccelScale);
+  buf = buf.subspan(4);
+  double y_accel = ConvertValue32(buf, kAccelScale);
+  buf = buf.subspan(4);
+  double z_accel = ConvertValue32(buf, kAccelScale);
+  buf = buf.subspan(4);
+  double temp = ConvertValue16(buf, kTempScale);
+  buf = buf.subspan(2);
+  uint16_t data_counter;
+  memcpy(&data_counter, buf.data(), sizeof(data_counter));
+  buf = buf.subspan(2);
+  uint32_t pico_timestamp;
+  memcpy(&pico_timestamp, buf.data(), sizeof(pico_timestamp));
+  buf = buf.subspan(4);
+  int16_t encoder1_count;
+  memcpy(&encoder1_count, buf.data(), sizeof(encoder1_count));
+  buf = buf.subspan(2);
+  int16_t encoder2_count;
+  memcpy(&encoder2_count, buf.data(), sizeof(encoder2_count));
+  buf = buf.subspan(2);
+  uint32_t checksum;
+  memcpy(&checksum, buf.data(), sizeof(checksum));
+  buf = buf.subspan(4);
+
+  CHECK(buf.empty()) << "Have leftover bytes: " << buf.size();
+
+  u_int32_t calculated_checksum = aos::ComputeCrc32(message.subspan(8, 38));
+
+  if (checksum != calculated_checksum) {
+    this->failed_checksums_++;
+  }
+
+  const auto diag_stat_offset = PackDiagStat(fbb, diag_stat);
+
+  frc971::IMUValues::Builder imu_builder(*fbb);
+
+  if (checksum == calculated_checksum) {
+    constexpr uint16_t kChecksumMismatch = 1 << 0;
+    bool imu_checksum_matched = !(diag_stat & kChecksumMismatch);
+
+    // data from the IMU packet
+    if (imu_checksum_matched) {
+      imu_builder.add_gyro_x(x_gyro);
+      imu_builder.add_gyro_y(y_gyro);
+      imu_builder.add_gyro_z(z_gyro);
+
+      imu_builder.add_accelerometer_x(x_accel);
+      imu_builder.add_accelerometer_y(y_accel);
+      imu_builder.add_accelerometer_z(z_accel);
+
+      imu_builder.add_temperature(temp);
+
+      imu_builder.add_data_counter(data_counter);
+    }
+
+    // extra data from the pico
+    imu_builder.add_pico_timestamp_us(pico_timestamp);
+    imu_builder.add_left_encoder(-encoder_scalar_ * encoder2_count);
+    imu_builder.add_right_encoder(encoder_scalar_ * encoder1_count);
+    imu_builder.add_previous_reading_diag_stat(diag_stat_offset);
+  }
+
+  // extra data from us
+  imu_builder.add_monotonic_timestamp_ns(driver_timestamp);
+  imu_builder.add_failed_checksums(failed_checksums_);
+  imu_builder.add_checksum_failed(checksum != calculated_checksum);
+
+  return imu_builder.Finish();
+}
+
+flatbuffers::Offset<frc971::ADIS16470DiagStat> Imu::PackDiagStat(
+    flatbuffers::FlatBufferBuilder *fbb, uint16_t value) {
+  frc971::ADIS16470DiagStat::Builder diag_stat_builder(*fbb);
+  diag_stat_builder.add_clock_error(value & (1 << 7));
+  diag_stat_builder.add_memory_failure(value & (1 << 6));
+  diag_stat_builder.add_sensor_failure(value & (1 << 5));
+  diag_stat_builder.add_standby_mode(value & (1 << 4));
+  diag_stat_builder.add_spi_communication_error(value & (1 << 3));
+  diag_stat_builder.add_flash_memory_update_error(value & (1 << 2));
+  diag_stat_builder.add_data_path_overrun(value & (1 << 1));
+  diag_stat_builder.add_checksum_mismatch(value & (1 << 0));
+  return diag_stat_builder.Finish();
+}
+
+double Imu::ConvertValue32(absl::Span<const uint8_t> data,
+                           double lsb_per_output) {
+  int32_t value;
+  memcpy(&value, data.data(), sizeof(value));
+  return static_cast<double>(value) * lsb_per_output;
+}
+
+double Imu::ConvertValue16(absl::Span<const uint8_t> data,
+                           double lsb_per_output) {
+  int16_t value;
+  memcpy(&value, data.data(), sizeof(value));
+  return static_cast<double>(value) * lsb_per_output;
+}
+
+Imu::~Imu() { PCHECK(0 == close(imu_fd_)); }
+
+}  // namespace frc971::imu