Device driver for a Philips PCD8544-based 48x84x1 display.

This is mainly the Nokia 3310 and 5510 displays you commonly find around the net.

API Summary

PCD8544_DRIVER_t PCD8544 device driver class
pcd8544_power_up Power up display
pcd8544_set_bias Write the PCD8544 bias setting
pcd8544_set_polarity Write the PCD8544 polarity
pcd8544_setup_begin_spi Start initialization of PCD8544 display
pcd8544_setup_end Finish initialization of PCD8544 display