st20-gp1 STMicroelectronics, st20-gp1 Datasheet - Page 5

• Manufacturer Part Number: st20-gp1
• Description: Gps Processor
• Manufacturer: STMicroelectronics

1
The ST20-GP1 is an application-specific single chip micro using the ST20 CPU with
microprocessor style peripherals added on-chip. It incorporates DSP hardware for processing the
signals from GPS (Global Positioning System) satellites.
The twelve channel GPS correlation DSP hardware is designed to handle twelve satellites, two of
which can be initialized to support the RTCA-SC159 specification for WAAS (Wide Area
Augmentation Service) and EGNOS (European Geostationary Navigation Overlay System)
services.
The ST20-GP1 has been designed to minimize system costs and reduce the complexity of GPS
systems. It offers all hardware DSP and microprocessor functions on one chip. Whilst the entire
analogue section, RF and clock generation are available on a companion chip. Thus, with the
addition of a ROM and a RAM chip, a complete GPS system is possible using just four chips, see
Figure 1.1.
The ST20-GP1 supports large values of frequency offset, allowing the use of a very low cost
oscillator, thus saving the cost of a Temperature Controlled Crystal Oscillator (TCXO).
The CPU and software have access to the part-processed signal to enable accelerated acquisition
time.
The ST20-GP1 can implement the GPS digital signal processing algorithms using less than 50% of
the available CPU processing power. This leaves the rest available for integrating OEM application
functions such as route-finding, map display and telemetry. A hardware microkernel in the ST20
Introduction
Antenna
Single chip
No TCXO
crystal
Radio
Low
cost
ST20-GP1
ROM
ASIC
DSP
Figure 1.1 GPS system
Watchdog
CPU
timer
RAM
Real
time
clock
UART
(optional)
Parallel I/O
Driver
ST20-GP1
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