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Old 07-30-2014, 05:00 PM   #861 (permalink)
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The power section is identical in this case. What is the normal output voltages for tx and rx for the outside world? I've never checked.

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Old 07-31-2014, 02:03 AM   #862 (permalink)
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The power section is identical in this case. What is the normal output voltages for tx and rx for the outside world? I've never checked.
Wiki says "Valid signals are either in the range of +3 to +15 volts or the range −3 to −15 volts with respect to the ground/common pin; consequently, the range between −3 to +3 volts is not a valid RS-232 level."
However some devices won't work with levels as low as +- 3v.
Normally there would be a MAX232 chip or equivalent in the circuit that takes logic voltage levels and makes the +- 12v signals.
I think flores would like access to the logic level (3.3v) rather than the +-12v.
So maybe a header with the logic level rx, tx and gnd seperate to the header with the rs232 compatible +- 12v signals.
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Old 07-31-2014, 09:17 AM   #863 (permalink)
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Flores, so you put the resistor divider on the RX and TX pins of the micro, and not on the lines that actually leave the board? Or was on the lines that leave the board? So, If I use the pins that are leaving the board, the separate header would need a voltage divider that goes from 12v down to 3.3v? And if I just bypass the MAX232, the divider would have to go from 5v down to 3.3v?
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Old 07-31-2014, 09:43 AM   #864 (permalink)
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yes yes.. If it was for me the max232 could be left out... dont no need for rs232 with the raspberry

And actually only the tx is an output so that would need a voltage divider. The rx is a input so no divider on that, 3.3 will trigger a pulse.. a voltage divider would make the signal to weak.
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Old 07-31-2014, 10:40 AM   #865 (permalink)
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I'm almost done adding a new connector with voltage divider. So, Flores' rx pin coming from off of the board goes straight to the microcontroller, and is going to be a well behaved 5v signal? Or do I have Flores' RX signal from off the board go to the max232? And the tx signal coming from the microcontroller to off of the board will be a 3.3v, skipping the max232 altogether.
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Last edited by MPaulHolmes; 07-31-2014 at 10:51 AM..
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Old 08-01-2014, 05:27 AM   #866 (permalink)
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Yes skip it.... the raspberry outputs 3.3v so that must NOT go to the max232.. must be connected directly to the micro.
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Old 08-01-2014, 05:31 AM   #867 (permalink)
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But RX still goes to the max232?
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Old 08-01-2014, 07:31 AM   #868 (permalink)
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But RX still goes to the max232?
I am picturing something like this. Would that be close flores?
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Old 08-04-2014, 04:13 AM   #869 (permalink)
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Yes.. plus the voltage divider on the tx.. like so:

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Old 08-06-2014, 11:33 AM   #870 (permalink)
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I just collected my AC motor for the ev. It's a 132m frame 75kw rewound industrial motor which comes fitted with an encoder bearing. The encoder is 64 ppr. Will this be enough or will i need to add an external encoder with more pulses per revolution?
The encoder bearing is the same one as this eBay listing.
NEW SKF Sensor Bearing BMB 6206 064S2 UA002A Electric Motor Bearing | eBay

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