AC Parameters

13.6.1Asynchronous Signal Timing Descriptions

nPWAIT is an input and is received through a synchronizer. As such, it has no setup and hold specification. The user must adhere to the protocol definition.

When the peripheral pins are in GPIO mode, they are read or written under software control. As outputs, they are driven valid on the pin approximately 20 ns after they are written by software. When inputs, they are received by a synchronizer and must be valid for approximately 20 ns before they are able to be recognized by a CPU read.

nRESET must remain asserted for 150 ms after VDD and VDDX are stable to properly reset the SA-1100.

nRESET_OUT is asserted for all types of reset (hard, watchdog, sleep, and software) and appears on the pin asynchronously to all clocks.

BATT_FAULT and VDD_FAULT are asynchronous inputs and are synchronized to the

32.768-kHz clock after entering the SA-1100. They must be valid for approximately 60 ms before they are recognized by the SA-1100.

PWR_EN asserts when the SA-1100 enters sleep mode and is driven onto the pin following the rising edge of the 32.768-kHz clock. It negates on the same edge as sleep mode is exited.

GP<27:0> are read and written under software control. In addition, an asynchronous edge detect may be performed. When writing a value to these pins, the pin transitions approximately 20 ns after the write is performed. When reading these pins, the signal is first synchronized to the internal memory clock and must be valid for at least 20 ns before it is visible to a processor read. For edge detects, the value on the pin following an edge must be stable for at least 10 ns for the edge to be caught by the edge detect circuit.

UDC+, UDC-, TXD_1, RXD_1, TXD_2, RXD_2, TXD_3, and RXD_3 are asynchronous relative to any device outside the SA-1100. The output pins, like all outputs on the SA-1100, have been characterized while driving a 50-pF lumped load capacitance.

SA-1100 Developer’s Manual

13-5

Page 353
Image 353
Intel SA-1100 manual Asynchronous Signal Timing Descriptions