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Co-authored-by: Jonas Schievink <jonasschievink@gmail.com>
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Jorge Aparicio 2020-07-13 15:45:59 +00:00 committed by GitHub
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3
embedded-workshop-book/src/get-descriptor-config.md
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@ -2,7 +2,7 @@
When the host issues a GET_DESCRIPTOR *Configuration* request the device needs to respond with the requested configuration descriptor *plus* all the interface and endpoint descriptors associated to that configuration descriptor during the DATA stage.
A GET_DESCRIPTOR Configuration request is a GERT_DESCRIPTOR request where the descriptor type encoded in the high bit of `wValue` is CONFIGURATION.
A GET_DESCRIPTOR Configuration request is a GET_DESCRIPTOR request where the descriptor type encoded in the high bit of `wValue` is CONFIGURATION.
We have covered configurations and endpoints but what is an *interface*?
@ -80,4 +80,3 @@ The interface descriptor in the response should contain these fields:
Again, we strongly recommend that you use the `usb2::configuration::Descriptor` and `usb2::interface::Descriptor` abstractions here. Each descriptor instance can be transformed into its byte representation using the `bytes` method -- the method returns an array. To concatenate both arrays you can use an stack-allocated [`heapless::Vec`] buffer. If you haven't the `heapless` crate before you can find example usage in the the `src/bin/vec.rs` file.
[`heapless::Vec`]: https://docs.rs/heapless/0.5.5/heapless/struct.Vec.html

3
embedded-workshop-book/src/setup-stage.md
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@ -15,7 +15,7 @@ The definition of `Descriptor::Configuration` as well as the associated test has
Your task now is to parse the data of this SETUP stage. We will start with the GET_DESCRIPTOR request, which is described in detail in section 9.4.3 of the USB specification. All the constants you will need are described in Tables 9-3, 9-4 and 9-5.
The fields of a GET_DESCRIPTOR request are as follows:
- `bmrequesttype` is 0b10000000
- `bmRequestType` is 0b10000000
- `bRequest` is GET_DESCRIPTOR
- the high byte of `wValue` contains the descriptor type, whereas the low byte contains the descriptor index
- `wIndex` is set to 0 for our purposes
@ -56,4 +56,3 @@ INFO:usb_2 -- Goal reached; move to the next section
You can find a solution to step 1. in `advanced/common/usb/get-descriptor-device.rs`.
You can find a solution to step 2. in `advanced/firmware/src/bin/usb-2-solution.rs`.