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UART voltage level


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#1 Nissim

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Posted 17 October 2011 - 12:29 AM

Hi There I have GPS module TTL output connected to my Netduino Mini. I connected(Tx) from GPS to pin 12 of Mini (Rx) . On my oscilloscope I measure data received at +2vdc level to GND . The mini does not accept the data as valid. I tried pull up resistor and LEDs on Rx of Mini line but no change. I tested the output of GPS with MAS232 to PC serial port I get good results ( as expected ) Any idea what is going on ? Kind regards Nissim

#2 Chris Walker

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Posted 17 October 2011 - 12:44 AM

Hi Nissim, If the GPS is only outputting 2V instead of 3.3V, the voltage may not be strong enough to register with the Netduino. According to page 610 of the microcontroller datasheet, a voltage of exactly 2.0 volts will register as "high" on the SAM7X MCU. ~2V may not be strong enough. http://www.atmel.com...nts/doc6120.pdf If you deploy/debug via TTL (pins 11/12) and hook the GPS up to the RS232 com port (pins 1/2) using your MAX232 circuit...does that work for you? Chris

#3 Nissim

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Posted 17 October 2011 - 04:11 AM

Thank you Chris I tested the very same code with Netduino Plus and I get good results I changed one line for Netduino Mini using SecretLabs.NETMF.Hardware.NetduinoMini; and I do not get same results as with Netduino plus I am wondering about deploy/debug via pins 1/2 which I am using for testing after deployment is successful. I can not see how to deploy to pins 11/12 TTL level- do I need extra hardware MAX232 ? Many thanks

#4 Nissim

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Posted 21 October 2011 - 11:14 PM

All problems related to receiving data from uart solved once I have downloaded the latest ER_CONFIG and ER_FLASH. To save yourself hours of mucking around debugging your own code - download latest files to override default original files supplied with min. cheers Nissim




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