Pololu Qik 2s9v1 Manuel d'utilisateur télécharger pdf (Page 9)

3.d. Jumpers

The qik jumpers allow you to easily alter the behavior of the device. These jumpers can be left off for most

applications. If you use a jumper, it must be in place when the unit first starts up; changing the jumpers while

the unit is running does not take effect until the qik is reset or power is cycled. The only exception to this is the

removal of the demo mode jumper while the qik is in demo mode, which takes the qik out of demo mode.

Fixed-Baud Mode

The jumper labeled A on the bottom of the qik (i.e. the one closest to the edge of the board) sets the qik to

fixed-baud mode when the shorting block is in place. When the shorting block is absent, the qik is auto-detect

mode and determines the baud rate automatically when it receives the first 0xAA (170) byte. If you have a noisy

serial connection or find that the automatic baud detection is not working well for your application, you can use a

shorting block or some other jumper to ground pin A (the circular pin right next to the “A” silkscreen label). This

fixes the qik’s baud rate at 38,400 bps, and the qik skips the automatic baud detection phase that normally occurs

on start-up.

Enable-CRC Mode

The jumper labeled B on the bottom of the qik enables cyclic redundancy check (CRC) mode when the shorting

block is in place. This allows you to increase the robustness of your qik connection through the addition of a CRC

error-checking byte to the end of the command packets you send to the qik. The default behavior of the qik is to

simply respond to a command packet once it receives the last byte. Grounding pin CRC (the circular pad right

next to the “CRC” silkscreen label) causes the qik to expect an additional CRC byte at the end of every command

packet. The CRC byte is the result of a CRC-7 computation on the entire command packet, as described in Section

6. If this byte does not match the expected CRC, the qik ignores the command and uses the ERR pin to announce

a CRC error.

3. Connecting the Qik Page 9 of 24

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Pololu Qik 2s9v1 Manuel d'utilisateur Page 9