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vk4tec

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Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 09:15pm 03 May 2013

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Hello

I found a mini Maximite kit.

Does it have more than one com port ?

Which pins ?

I want to use it to go from GPS to another com port

USART compatible I am assuming

- Andrew -

Andrew Rich VK4TEC
www.tech-software.net

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 01:20am 04 May 2013

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Hi Andrew,
Yes, it has the normal two serial ports for the Maximite using MMBasic - one with hardware control lines, one without. Yes, USART compatible, running at TTL voltages and the logic levels "inverted" as normal for TTL. Following is from Geoff Graham's MMBasic Language Manual, App A (Srial Comms) p43 - downloadable from his website Geoff Graham.

The Silicon Chip article on the MINI Maximite is in the Nov. 2011 issue.
Have fun,
Greg

Edit: you may need a pullup resistor on the Maximite transmit pins, 16 &/or 18 for COM1 and COM2 respectively, although I didn't when talking to a USART on an Atmel Mega chip.

Input/Output Pin Allocation
COM1: uses pin 15 for receive data (data in) and pin 16 for transmit data (data out). If flow control is specified
pin 17 will be used for RTS (receive flow control � it is an output) and pin 18 will be CTS (transmit flow
control � it is an input). If the Data output Enable (DE) signal for RS485 is enabled it will be on pin 17.
COM2: uses pin 19 for receive data (data in) and pin 20 for transmit data (data out) in the monochrome
Maximite and D0 for receive data and pin D1 for transmit data on the Colour Maximite.
For the DuinoMite see the "DuinoMite MMBasic ReadMe.pdf" document for details.
When a serial port is opened the pins used by the port are automatically set to input or output as required and
the SETPIN and PIN commands are disabled for the pins. When the port is closed (using the CLOSE
command) all pins used by the serial port will be set to a not-configured state and the SETPIN command can
then be used to reconfigure them.
The signal polarity is standard for devices running at TTL voltages (not RS232). Idle is voltage high, the start
bit is voltage low, data uses a high voltage for logic 1 and the stop bit is voltage high. The flow control pins
(RTS and CTS) use a low voltage to signal stop sending data and high as OK to send. These signal levels allow
you to directly connect to devices like the EM-408 GPS module (which uses TTL voltage levels).

Edited by paceman 2013-05-05

vk4tec

Senior Member

Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 03:28pm 12 May 2013

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Thanks Greg.

I have

1. TTL GPS
2. TTL TX module
3. 3.3 Volts PSU from 5 - 16 volts.

I want to use the mini Maximite bacause of its size and ease of use ie basic.

I am hesitant to cut of the extra part of the board for the time being.

Making a GPS transmitter for my DJI Phantom Quad Copter

- Andrew -

Andrew Rich VK4TEC
www.tech-software.net

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 12:59am 13 May 2013

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Looks like you're all set - and sounds like fun!
There is example code for GPS in the MMBasic library MMBasic Library written by Geoff Graham. There have also been a number of other posts about different GPS modules in this forum - try searching "gps".

I haven't cut my Mini either - I might need that bit of space later!
Greg

vk4tec

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Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 01:17am 13 May 2013

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Oh I have done gps and lcd

Heck I even did eta code as well

But this will be the first time I have flown a maximite on an rc chopper

Andrew

Andrew Rich VK4TEC
www.tech-software.net

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 01:52am 13 May 2013

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Just checked your profile Andrew - comments about grandmothers and egg sucking come to mind

When you get it flying post us all some YouTube video!

vk4tec

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Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 06:03am 13 May 2013

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Andrew Rich VK4TEC
www.tech-software.net

vk4tec

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Joined: 24/03/2012
Location: Australia
Posts: 239

Posted: 10:34pm 13 May 2013

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Ok success

All is working great

TX is sending at 19k2 434 MHz

GPS is wired up and working great

Power can get down to about 5 volts before drop out

- Andrew-

Andrew Rich VK4TEC
www.tech-software.net

paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329

Posted: 12:06am 14 May 2013

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Have you got a hookup diagram and a list of the modules Andrew, and cost? It would be a great addition for the library - the first model and radio control project. Maybe after you get it all flying!

Greg

Nixie
Regular Member

Joined: 19/02/2013
Location: Australia
Posts: 66

Posted: 03:05am 24 Jun 2013

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Andrew, I'm interested to know what type of GPS you are using (EM406A?) and if you ended up connecting it directly to the COM port pins; and with, or without pull-up resistors?

Regards, Nic VK3COW (ex VK4DIT)

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