PIC developers don't have to wait for USB support in microchip's product line any longer. The Full-Speed USB PIC family, which comprises four chips so far, is topped by the 48-MHz PIC18F4550.
This chip has 32 kbytes of flash, 2 kbytes of RAM, and 256 bytes of EEPROM. It also has a 13-channel, 10-bit analog-to-digital converter and dual comparators.
Overall, the family's dual serial ports can handle the multidrop RS-485 and autobaud-based LIN protocol. Its dual synchronous ports handle I2C and serial-peripheral-interface protocols.
The 12-Mbit/s USB support includes on-chip transceivers and a 1-kbyte dual-port buffer than can also be used as general-purpose memory. The hardware supports 16 input and 16 output USB end points with individual interrupts so applications can handle multiple communication links.
Parallel streaming port support is available for high-speed transfers. With it, data can move to or from an I/O port and a USB endpoint. This is especially useful when streaming data from an external codec or peripheral. Transfers occur directly between the port and the USB controller and do not impact the performance of the PIC processor. The overhead and operation of the streaming port are similar to DMA services on other chips.
The chips are based on Microchip's Nanowatt technology, which features multiple power-down modes and low-voltage support. Peripheral power and clocks are controlled individually, enabling the processor to sleep until a USB interrupt. Pricing for the Full-Speed USB PIC family starts at $4.75. The chip works with standard serial drivers. Custom USB driver support is available.