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nRF24AP2-USB Product Specification

Use the Set_Descriptor_String(0xC7) command to configure USB descriptor strings. This command is an

extension to the ANT command interface and is sent in the same manner as the other ANT serial com-

mands. The descriptor strings can be set up to three times. See the document ANT Message Protocol and

Usage for further details on the command library.

Note: Do not remove power supply while updating the VID, PID or USB descriptors.

5.3.6

Control transfer

Control transfers are used for all commands and queries during the USB device enumeration process.

The nRF24AP2-USB allows a maximum data packet size of 32 bytes for the control transfers. All control

transfers can have up to three stages, and are handled automatically by the nRF24AP2-USB.

5.3.6.1

Control write transfer

Figure 13. Setup stage

The setup stage starts with a SETUP token packet, followed by a DATA packet detailing the type of

request. Finally an ACK handshake packet is sent back by the nRF24AP2-USB if the setup data has been

received correctly, otherwise nothing is sent back.

Figure 14. Data stage (optional)

When the request indicates that the host wants to send control data, the data stage will be made up of one

or more OUT transfers. Each OUT transfer will start with an OUT token packet followed by a DATA packet.

The nRF24AP2-USB will reply with an ACK handshake packet if everything was received correctly. A NAK

will be returned if the previous packet from the host is still being processed. If any part of the token or data

packet was corrupted or missing, nothing will be sent back. A STALL will be returned if the token and data

were received but another error occurred.

ACK

SETUP

nRF24AP2-USB

Host

DATA0

ACK

OUT

DATAx

STALL

(error)

NAK

(not ready)