diff --git a/frc971/wpilib/gyro_interface.cc b/frc971/wpilib/gyro_interface.cc
new file mode 100644
index 0000000..4b440a9
--- /dev/null
+++ b/frc971/wpilib/gyro_interface.cc
@@ -0,0 +1,144 @@
+#include "frc971/wpilib/gyro_interface.h"
+
+#include <inttypes.h>
+
+#include "aos/common/logging/logging.h"
+#include "aos/common/time.h"
+
+#ifndef M_PI
+#define M_PI 3.14159265358979323846
+#endif
+
+namespace frc971 {
+namespace wpilib {
+
+GyroInterface::GyroInterface() : gyro_(new SPI(SPI::kOnboardCS0)) {
+  // The gyro goes up to 8.08MHz.
+  // The myRIO goes up to 4MHz, so the roboRIO probably does too.
+  gyro_->SetClockRate(4e6);
+  gyro_->SetChipSelectActiveLow();
+  gyro_->SetClockActiveHigh();
+  gyro_->SetSampleDataOnRising();
+  gyro_->SetMSBFirst();
+}
+
+bool GyroInterface::InitializeGyro() {
+  uint32_t result;
+  if (!DoTransaction(0x20000003, &result)) {
+    LOG(WARNING, "failed to start a self-check\n");
+    return false;
+  }
+  if (result != 1) {
+    // We might have hit a parity error or something and are now retrying, so
+    // this isn't a very big deal.
+    LOG(INFO, "gyro unexpected initial response 0x%" PRIx32 "\n", result);
+  }
+
+  // Wait for it to assert the fault conditions before reading them.
+  ::aos::time::SleepFor(::aos::time::Time::InMS(50));
+
+  if (!DoTransaction(0x20000000, &result)) {
+    LOG(WARNING, "failed to clear latched non-fault data\n");
+    return false;
+  }
+  LOG(DEBUG, "gyro dummy response is 0x%" PRIx32 "\n", result);
+
+  if (!DoTransaction(0x20000000, &result)) {
+    LOG(WARNING, "failed to read self-test data\n");
+    return false;
+  }
+  if (ExtractStatus(result) != 2) {
+    LOG(WARNING, "gyro first value 0x%" PRIx32 " not self-test data\n", result);
+    return false;
+  }
+  if (ExtractErrors(result) != 0x7F) {
+    LOG(WARNING, "gyro first value 0x%" PRIx32 " does not have all errors\n",
+        result);
+    return false;
+  }
+
+  if (!DoTransaction(0x20000000, &result)) {
+    LOG(WARNING, "failed to clear latched self-test data\n");
+    return false;
+  }
+  if (ExtractStatus(result) != 2) {
+    LOG(WARNING, "gyro second value 0x%" PRIx32 " not self-test data\n",
+        result);
+    return false;
+  }
+
+  return true;
+}
+
+bool GyroInterface::DoTransaction(uint32_t to_write, uint32_t *result) {
+  static const uint8_t kBytes = 4;
+  static_assert(kBytes == sizeof(to_write),
+                "need the same number of bytes as sizeof(the data)");
+
+  if (__builtin_parity(to_write & ~1) == 0) to_write |= 1;
+
+  uint8_t to_send[kBytes], to_receive[kBytes];
+  const uint32_t to_write_flipped = __builtin_bswap32(to_write);
+  memcpy(to_send, &to_write_flipped, kBytes);
+
+  switch (gyro_->Transaction(to_send, to_receive, kBytes)) {
+    case -1:
+      LOG(INFO, "SPI::Transaction failed\n");
+      return false;
+    case kBytes:
+      break;
+    default:
+      LOG(FATAL, "SPI::Transaction returned something weird\n");
+  }
+
+  memcpy(result, to_receive, kBytes);
+  if (__builtin_parity(*result & 0xFFFF) != 1) {
+    LOG(INFO, "high byte parity failure\n");
+    return false;
+  }
+  if (__builtin_parity(*result) != 1) {
+    LOG(INFO, "whole value parity failure\n");
+    return false;
+  }
+
+  *result = __builtin_bswap32(*result);
+  return true;
+}
+
+uint16_t GyroInterface::DoRead(uint8_t address) {
+  const uint32_t command = (0x8 << 28) | (address << 17);
+  uint32_t response;
+  while (true) {
+    if (!DoTransaction(command, &response)) {
+      LOG(WARNING, "reading 0x%" PRIx8 " failed\n", address);
+      continue;
+    }
+    if ((response & 0xEFE00000) != 0x4E000000) {
+      LOG(WARNING, "gyro read from 0x%" PRIx8
+                   " gave unexpected response 0x%" PRIx32 "\n",
+          address, response);
+      continue;
+    }
+    return (response >> 5) & 0xFFFF;
+  }
+}
+
+double GyroInterface::ExtractAngle(uint32_t value) {
+  const int16_t reading = -(int16_t)(value >> 10 & 0xFFFF);
+  return static_cast<double>(reading) * 2.0 * M_PI / 360.0 / 80.0;
+}
+
+uint32_t GyroInterface::ReadPartID() {
+  return (DoRead(0x0E) << 16) | DoRead(0x10);
+}
+
+uint32_t GyroInterface::GetReading() {
+  uint32_t result;
+  if (!DoTransaction(0x20000000, &result)) {
+    return 0;
+  }
+  return result;
+}
+
+}  // namespace wpilib
+}  // namespace frc971