080505
OPERATIONS MANUAL PPM-GX500
11
Audio Interface
The PPM-GX500 has an audio interface designed to provide high-quality audio
reproduction for embedded systems use. The PPM-GX500 provides a 2-channel line
level input, 2-channel line level output and microphone input.
J102
(on the bottom side of the board) provides connection to the audio interface.
Visual
Index
GPS Interface
The PPM-GX500 board has provisions for supporting the Lassen
®
IQ GPS receiver
module. The necessary serial interface is terminated to an 8-pin header connector
(
J108
) compatible with the GPS receiver. The receiver module and a sample antenna
are available from WinSystems (Part# KIT-GPS-1). Contact your WinSystems’
Applications Engineer for additional information.
The optional GPS can also provide a pulse per second (PPS) interrupt. The receiver
generates a 4 µs wide, positive pulse every second with the leading edge synchronized
to UTC time within ±95 ns when valid position fixes are being reported. WinSystems’
on-board implementation degrades this accuracy by buffering the PPS output using
a 74HCT14 Schmitt trigger device which also inverts the signal. Since PC interrupts
are edge-triggered on the rising edge, the actual interrupt will occur 4 µs plus the
inverter propagation time later (typically 17 nS). This added delay is insignificant to
any software synchronizing routines as the entire hardware interrupt acknowledgement
process will consume many additional microseconds in a best-case scenario. The PPS
signal begins immediately at power-up and continues even if the receiver loses GPS
lock. The drift of the signal without GPS lock is unspecified.
Visual
Index
LINE_L
LINE_R
GND
OUT_L
OUT_R
GND
GND
GND
MIC1
MIC1_PWR
J102
9 7 5 3 1
o o o o o
o o o o o
10 8 6 4 2
