constants.m

基于串行接口的GPS驱动程序

function Constants
% This M-file defines global constants for the numeric values in
% the GPS communication protocols. These values have been tested with
% Garmin brand GPS systems (specifically, the eTrex Venture).

% Basic Packet Identifiers
global pid_etx_byte pid_ack_byte pid_dle_byte pid_nak_byte
global pid_protocol_array pid_product_rqst pid_product_data

pid_etx_byte = 3;    % ASCII ETX (End of text)
pid_ack_byte = 6;    % ASCII ACK (Acknowledge)
pid_dle_byte = 16;   % ASCII DLE (Data link escape)
pid_nak_byte = 21;   % ASCII NAK (Not acknowledge)
pid_protocol_array = 253;
pid_product_rqst = 254;
pid_product_data = 255;

% Link Protocol 1
global pid_command_data pid_xfer_cmplt pid_date_time_data pid_position_data
global pid_prx_wpt_data pid_records pid_rte_hdr pid_rte_wpt_data 
global pid_almanac_data pid_trk_data pid_wpt_data pid_pvt_data 
global pid_rte_link_data pid_trk_hdr

pid_command_data    = 10;
pid_xfer_cmplt      = 12;
pid_date_time_data  = 14;
pid_position_data   = 17;
pid_prx_wpt_data    = 19;
pid_records         = 27;
pid_rte_hdr         = 29;   
pid_rte_wpt_data    = 30;
pid_almanac_data    = 31;
pid_trk_data        = 34;
pid_wpt_data        = 35;
pid_pvt_data        = 51;
pid_rte_link_data   = 98;
pid_trk_hdr         = 99;

% Device Command Protocol 1 (A010)
global cmd_abort_transfer cmd_transfer_alm cmd_transfer_posn cmd_transfer_prx
global cmd_transfer_rte cmd_transfer_time cmd_transfer_trk cmd_transfer_wpt
global cmd_turn_off_pwr cmd_start_pvt_data cmd_stop_pvt_data

cmd_abort_transfer  = 0;
cmd_transfer_alm    = 1;    % Almanac
cmd_transfer_posn   = 2;    % Position
cmd_transfer_prx    = 3;    % Proximity waypoints
cmd_transfer_rte    = 4;    % Routes
cmd_transfer_time   = 5;    % Current time
cmd_transfer_trk    = 6;    % Track log
cmd_transfer_wpt    = 7;    % Waypoints
cmd_turn_off_pwr    = 8;    % Turn off device power
cmd_start_pvt_data  = 49;   % Begin transfer of PVT data
cmd_stop_pvt_data   = 50;   % End transfer of PVT data