Driver IC with automatic token direction self-sensing circuitry

In an LED printhead or the like, a plurality of LED arrays are arranged in a row. Opposite the LED arrays are driver IC chips providing current in respective current driving channels to respective LEDS. Current to an LED for recording of a pixel will be provided for say a duration related to a multibit image data signal. A data bus is provided for carrying the data signals. The data signals are latched in respective data registers associated with each current driving channel. A token bit shift register is provided for identifying a respective data register for latching of the multibit image data signal presently on the data bus. A direction of shifting of the token bit is determined through automatic self-sensing of the token bit itself as the token bit is moved from a boundary scan register that forms a part of a boundary scan test architecture.