The qik has seven LEDs that are used to provide feedback about its state of operation:
Automatic Baud Detection Phase
When the qik first starts up in automatic baud detection mode, it enters a phase in which it is waiting to receive the byte 0xAA (170 in decimal) at a baud rate that is within the range of 1200 bps to 115,200 bps. If the serial receive line RX is pulled high, as is expected for an idle TTL serial line and the default state of an unconnected RX, the green status LED fades in and out evenly every 0.8 s. If the serial receive line, RX, is held low (or, equivalently, the SIN line is held high), this is indicative of a bad serial connection and the red error LED cycles between being on for 0.4 s and off for 0.4 s (with the green status LED off).
If a serial byte other than 0xAA is received in this mode, or if 0xAA is transmitted at an invalid baud rate, the red error LED turns on and stays on until the automatic baud detection phase ends. This gives you feedback that the baud has not yet successfully been set and the controller is still in the automatic detection phase. Once the baud is detected, this phase ends and the qik proceeds to normal operation.
In normal operation, the green status LED very briefly flashes a heartbeat every 1.3 seconds. If the qik is in enable-CRC mode, the heartbeat LED flickers twice in rapid succession; if not, it pulses just once per heartbeat. If any serial activity is detected, the green status LED turns on until the next heartbeat turns it off. If an error occurs, the red error LED turns on and remains on until you issue a get-error command (see Section 5.c).
In demo mode, the status and error LEDs cycle through the pattern:
This cycle takes five seconds, and each of the four LED states corresponds to a different output state of the qik’s motor ports. When the red error LED is on, motor M0 is active, and when the red error LED is off, motor M1 is active. When the green status LED is on, the active motor is moving forward, and when the green status LED is off, the active motor is moving in reverse. If you don’t have any motors connected, the motor indicator LEDs light according to this pattern, and you can see them fade in and out as the motor speed ramps up and back down.