App note from Holtek on their CAN Bus controller chip HT45B3305H. Link here (PDF)
Holtek has released a CAN Bus interface control device, the HT45B3305H. The CAN physical layer can support high-speed networks up to 1 Mbit/s and supports the CAN 2.0A/B protocol as well as conforming to the ISO11898-1:2003 specification. It has 32 internal channels (Message Objects) and provides data transmission and a Received Enhanced Full CAN architecture as well as SPI and I2C communication interfaces.