User manual

MCP250XX User’s Guide
DS51266C-page 20  2004 Microchip Technology Inc.
2.4 ESTABLISHING COMMUNICATIONS
When the software is started from a new template (as it must be the first time it is
started), some steps must be taken to insure proper operation and to set up the
software defaults. These defaults can be saved by saving the template as a project
and opening the project in subsequent sessions.
2.4.1 Configure Parallel Port
The board status (including parallel port address and connection status) is indicated in
the Board Status window (Figure 2-3). Assuming the port address, as displayed in the
window, matches the address as configured by the PC, the board status should
indicate “connected”, with the indicator in the window being green.
If the status indicator is red and indicates “not connected”, check the port address. To
change the port address that the software uses, select “Options > MCP2515” and enter
the correct port address in the appropriate dialog box (Figure 2-11).
FIGURE 2-11: PC NODE OPTIONS
2.4.2 Match Oscillator Frequency with Board
The CAN data rate is a function of the oscillator frequency. Therefore, the proper
oscillator frequency must be set in order for the software to calculate the CAN data rate
correctly. Open the same window that was opened to set the parallel port address
(Figure 2-11). The frequency of oscillation units are displayed in kilohertz (kHz).
Note: Port address is entered as a hex value.