Current Version:
2.0
Released 10/24/2002
Optimizing Serial Communications
The "Write ahead words" option under Programmer Setup determines how many words are written
to the PICSTART Plus device before waiting for confirmation from the device. This value defaults to 1,
which should work on virtually any PC regardless of its COM port settings. On some PCs you will be able
to get vastly better performance by increasing the write-ahead value, although other PCs will not work
reliably with anything other than the default value. Experiment at your own risk, and be sure to use only
Flash/EPROM parts (no OTP!) until you're sure your settings are reliable.
If you do experience communications errors, one additional thing to try is to disable your UART's FIFO
buffers:
- From the Windows "Start" menu, select "Control Panel" from the "Settings" submenu (Fig. 1).
| Figure 1 |
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- Open the "System" control panel applet (Fig. 2).
| Figure 2 |
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On Windows 2000
- Select the "Hardware" tab (Fig. 3.1), then select the "Device Manager" button (Fig. 3.2).
On Windows 98/ME
- Select the "Device Manager" tab (Fig. 3.3).
Figure 3.1 |
Figure 3.2 |
Figure 3.3 |
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- Expand the "Ports (COM & LPT)" list item (Fig. 4).
| Figure 4 |
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- Double-click on the COM port to which your PICSTART Plus is connected.
- Select the "Port Settings" tab (Fig. 5).
| Figure 5 |
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- Select the "Advanced..." button (Fig. 6).
| Figure 6 |
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- Uncheck the "Use FIFO buffers..." checkbox (Fig. 7) and select "OK".
| Figure 7 |
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If, after disabling the FIFO buffers, you still encounter communications errors, decrease the write-ahead setting until communication becomes reliable.