Archive for February, 2008
Sunday, February 24th, 2008
This one was pretty stupid really. The motor drivers are H-bridges made from complementary pairs of MOSFET (the Zetex ZXMC3A16DN8 (datasheet). These need a proper driver chip to ensure good turn-on and turn-off times because of the gate capacitance. for the driver, I used the common Maxim MAX4427 (datasheet). There ...
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Saturday, February 23rd, 2008
It was all getting too awkward. A bit of short sighted design on my part had the Nokia LCD sharing an SPI port with the motor encoders. This meant that I had to turn off the encoders to write to the LCD. While no motion information would be lost by ...
Posted in decimus | 5 Comments »
Friday, February 22nd, 2008
I like to check out the various Japanese micromouse builders's site to see what they are up to. Google translations sometimes make some sense but it is very hard work. I was looking on this blog the other day: R & D daily: work out. The author (whose name I ...
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Thursday, February 21st, 2008
Now that Decimus has all its bits fitted, it is time to get on with the more serious business of driving it about. The basic code for the motor PWM driver has been tested and suitable drive commands can be sent to them. Since this is a PWM system, a ...
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Thursday, February 21st, 2008
The LS7366 is a 32 bit counter with a direct interface for quadrature signals from incremental encoders. There is also an index channel for marker functions. The interface to the microcontroller is SPI mode 0 making it relatively easy to drive with a variety of common controllers. Decimus has ...
Posted in decimus | 4 Comments »
Wednesday, February 20th, 2008
I use SPI on my micromouse both to talk to the Nokia graphical LCD and to talk to the LS7366 quadrature encoders. A large number of devices can be connected to the SPI data lines, MOSI and MISO. Each device needs its own select line. This all appear very simple ...
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Sunday, February 17th, 2008
Decimus has one of the ADC inputs dedicated to monitoring the battery voltage. The batteries used in this micromouse are Lithium Polymer cells and it is particularly important that they are not allowed to discharge too far. Since the full battery voltage is about 7.4 Volts, this gets divided by ...
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Sunday, February 17th, 2008
Having installed the LCD, it was time to get the code working for it. First I realised that it may not have been so clever to put the LCD on the same SPI port as the encoders. This will mean that I have to take care that the encoders are ...
Posted in decimus | 4 Comments »
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