Link to issue number:

Closes #7721.

Summary of the issue:

From #7721 (comment)

For several braille displays, when sending a packet, the display acknowledges the receipt of a packet. This is a mechanism to make sure that a packet has been delivered to a braille display in a correct way. Several displays have such a feature, including Handy Tech, Eurobraille and Freedom Scientific displays.

Description of how this pull request fixes the issue:

This pr implements ACK packet handling on the main BrailleDisplayDriver class itself, rather than specific for every braille display. Currently, only the Handy Tech driver makes use of this generic functionality. This functionality will also be used for the Eurobraille braille display driver (#7488).

Testing performed:

Tested using a Handy Tech Basic Braille, which has some issues with updating the display if ACK handling is disabled. Difference between ACK handling enabled and disabled is clearly noticeable. Also tested in my eurobraille-native branch. The ACK timer is properly reset in case of a missed ack, and a debug warning is logged.

Known issues with pull request:

None i'm aware of.

Change log entry:

• Changes for developers:
  • Implemented a generic system in braille.BrailleDisplayDriver to deal with displays which send confirmation/acknowledgement packets. See the handyTech braille display driver as an example. (Native driver for Handy Tech braille displays #7590, Native braille display drivers: provide a generic way to handle acknowledgement packets. #7721)