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set-address.md: SET_ADDRESS Configuration -> prose

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Lotte Steenbrink 2020-07-13 17:02:13 +02:00
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embedded-workshop-book/src/set-address.md
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> This request should come right after the `GET_DESCRIPTOR Device` request if you're using Linux, or be the first request sent to the device by Mac OS.
Section 9.4.6, Set Address, describes how to handle this request but below you can find a summary:
A SET_ADDRESS request has the following fields as defined by Section 9.4.6 Set Address of the USB spec:
- `bmrequesttype` is 0b00000000
- `brequest` is SET_ADDRESS
- `wValue` contains the address to be used for all subsequent accesses
- `wIndex` and `wLength` are 0, there is no `wData`
It should be handled as follows:
- If the device is in the `Default` state, then
- if the requested address was `0` (`None` in the `usb` API) then the device should stay in the `Default` state
- if the requested address stored in `wValue` was `0` (`None` in the `usb` API) then the device should stay in the `Default` state
- otherwise the device should move to the `Address` state
- If the device is in the `Address` state, then
- if the requested address was `0` (`None` in the `usb` API) then the device should return to the `Default` state
- if the requested address stored in `wValue` was `0` (`None` in the `usb` API) then the device should return to the `Default` state
- otherwise the device should remain in the `Address` state but start using the new address
- If the device is in the `Configured` state this request results in "unspecified" behavior according to the USB specification. You should stall the endpoint in this case.