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rossfree
- 3rd May 2007, 16:00
Listed below are voltage measurements I took off of a MAX232. The circuit is a carbon copy of the bootloader circuit found on Mecanique's Microcode Studio Website:

http://www.mecanique.co.uk/code-studio/loader/index.html#Hardware%20Requirements

If you are having trouble getting your bootloader to work and you question your circuit, this information might help. I don't guarantee that this is accurate for all MAX232 circuits but if you see a voltage that strays considerably from those below, it might lead you to a circuit problem you can easily resolve.

All voltage measurements were taken with respect to circuit common (gnd). The circuit was connected to my computer via serial cable and com1. Running Windows XP Pro. Pins 11 and 12 connected to TX and RX of PIC (16f876). Pin 9 connected thru 100 ohm resistor to MCLR of Pic

MAX232 Pins / Voltages

pin 1 = 7.6 volts
___2 = 9.5
___3 = 2.8
___4 = 3.9
___5 = -5.0
___6 = -9.0
___7 = -9.0
___8 = -10.0
___9 = 5.0
___10 = -10.0
___11 = 5.0
___12 = 5.0
___13 = -10.0
___14 = -8.5
___15 = 0.0 (common gnd)
___16 = 5.0

I wish I had these when I was troubleshooting recently. Thought I would share. This is such a great place for information!

Ross