mirrors/embedded-trainings-2020
1
0
Fork 0
mirror of https://github.com/ferrous-systems/embedded-trainings-2020.git synced 2024-05-15 23:13:15 +00:00
Code Issues Projects Releases Wiki Activity

Merge pull request #94 from gdetrez/patch-1

Browse source 
Fix typos in beginner-next-steps.md
This commit is contained in:
James Munns 2020-08-04 23:42:48 +02:00 committed by GitHub
parent 175aa52dcc c72a79eb26
commit 7134ab798e
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
1 changed files with 2 additions and 2 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
embedded-workshop-book/src/beginner-next-steps.md
View file

@ -6,9 +6,9 @@ If you've already completed the main workshop tasks or would like to explore mor
If you check the API documentation of the `Radio` abstraction we have been using you'll notice that we haven't used these methods: `energy_detection_scan()`, `set_cca()` and `try_send()`.
The first method scans the currently selected channel (see `set_channe()l`), measures the energy level of ongoing radio communication in this channel and returns the maximum energy observed over a span of time. This method can be used to determine what the *idle* energy level of a channel is. If there's non-IEEE 802.15.4 traffic on this channel the method will return a high value.
The first method scans the currently selected channel (see `set_channel()`), measures the energy level of ongoing radio communication in this channel and returns the maximum energy observed over a span of time. This method can be used to determine what the *idle* energy level of a channel is. If there's non-IEEE 802.15.4 traffic on this channel the method will return a high value.
Under the 802.15.4 specification, before sending a data packet devices must first check if there's communication going on in the channel. This process is known as Clear Channel Assessment (CCA). The `send` method we have been used performs CCA in a loop and sends the packet only when the channel appears to be idle. The `try_send` method performs CCA *once* and returns the `Err` variant is the channel appears to be busy. In this failure scenario the device does not send any packet.
Under the 802.15.4 specification, before sending a data packet devices must first check if there's communication going on in the channel. This process is known as Clear Channel Assessment (CCA). The `send` method we have been used performs CCA in a loop and sends the packet only when the channel appears to be idle. The `try_send` method performs CCA *once* and returns the `Err` variant if the channel appears to be busy. In this failure scenario the device does not send any packet.
The `Radio` abstraction supports 2 CCA modes: `CarrierSense` and `EnergyDetection`. `CarrierSense` is the default CCA mode and what we have been using in this workshop. `CarrierSense` will only look for ongoing 802.15.4 traffic in the channel but ignore other traffic like 2.4 GHz WiFi and Bluetooth. The `EnergyDetection` method is able to detect ongoing non-802.15.4 traffic.