4359ba84ed
01942b89 add TODO b74a456a don't hardcode the lists ed5a4bf5 add face stds 396a2bb5 add can error counter to controlsState c6b5c73b Switch default to msgq (#21) a457ffa0 Fix indentation in readme.md a1fc8c75 explicitly mention Python for syntax colouring (#20) 19e23931 Fix expected for cameraOdometry and liveCalibration e7d2f978 Add radar comm issue error db64cd43 Reserve safety #21 for VAG PQ35/PQ46/NMS (#19) 79d638d5 separate honda safety models between Bosch Giraffe and Bosch Nidec 2614a650 better name b6b84cda add longitudinal 78f5934a Add canRxErrs to health 67588993 qlog liveCalibration df80b870 add more stuff to fw log in CarParams a87805ad fix doxs 4746b208 got doxed 21cf3f55 build on mac 31ac47c2 Add carUnrecognized event git-subtree-dir: cereal git-subtree-split: 01942b890d7acf19aecc09432fe5048ba21c0fc9 old-commit-hash: 9504037aa798e9adb12a2c7e769f42a57198b96a
What is cereal?
cereal is both a messaging spec for robotics systems as well as generic high performance IPC pub sub messaging with a single publisher and multiple subscribers.
Imagine this use case:
- A sensor process reads gyro measurements directly from an IMU and publishes a sensorEvents packet
- A calibration process subscribes to the sensorEvents packet to use the IMU
- A localization process subscribes to the sensorEvents packet to use the IMU also
Messaging Spec
You'll find the message types in log.capnp. It uses Cap'n proto and defines one struct called Event.
All Events have a logMonoTime and a valid. Then a big union defines the packet type.
Pub Sub Backends
cereal supports two backends, one based on zmq, the other called msgq, a custom pub sub based on shared memory that doesn't require the bytes to pass through the kernel.
Example
import cereal.messaging as messaging
# in subscriber
sm = messaging.SubMaster(['sensorEvents'])
while 1:
sm.update()
print(sm['sensorEvents'])
# in publisher
pm = messaging.PubMaster(['sensorEvents'])
dat = messaging.new_message()
dat.init('sensorEvents', 1)
dat.sensorEvents[0] = {"gyro": {"v": [0.1, -0.1, 0.1]}}
pm.send('sensorEvents', dat)