Wearwulf

The Communications Link

The LPC2106 processor has two built-in UARTS:

• UART0
  UART0 can be used to program the built-in FLASH memory with the initial application code. UART0 does not have hardware flow control.
• UART1
  UART1 has built-in hardware flow control. However this uses a number of additional pins which have alternate useful functions.

The Wearwulf wearable computer will only use UART0. This will minimize the number of pins in use, and allow code to be downloaded into the processor. The lack of hardware flow control may limit the throughput of data, however the data is buffered within the processor, and large quantites of data can be transferred via an MMC card.

A »MAXIM MAX3221E transceiver will be required to convert between the 3.3V processor logic pins, and the RS232 voltage levels. This device has an automatic shutdown, to reduce its power consumption, that activates within 30µs of the external serial device being disconnected. It also has the ability to indicate whether a signal is present, allowing the Wearwulf to detect whether it is connected to a serial device.