we are trying to connet an ultrasonic range finder (MaXSonar MB1340 http://maxbotix.com/documents/XL-MaxSonar-EZ_Datasheet.pdf) to the UART_A port of our Mastermind board (/dev/ttyS0). The sensor is powerred using the 5v and GND pins of the same port. The problem is that the sensor provides random values.
We have checked that the US sensor works fine in a laptop as well as checked the serial configuration: baud rate is 9600, 8 bits, no parity, one stop bit. Notice also that the ROS node that we are using works fine on another on-board computer that we have been using the last months.
At this point, we have some questions :
1.- The US sensor requires 3.4mA average current and 100mA peak. Is this current provided by the Mastermind UART ports?
2.- The US sensor datasheet says:"Although the voltage of 0-5v is outside the RS232 standard, most RS232 devices have sufficient margin to read 0-5v serial data. If standard voltage level RS232 is desired, invert, and connect an RS232 converter such as a MAX232." Does anybody know if that's the case of the Mastermind board?? We gues it is NOT, since the Mastermind Manual refers to the serial ports as "Serial interfaces: UART 5V voltage levels".
3.- The last question: in the tutorial for the onboard computer setup for using the Asctec MAV framework (http://wiki.ros.org/asctec_mav_framework/Tutorials/onboard_computer_setup) we have seen a Mastermind Specific Setup for configuring the serial ports for fast communication (5.2). Is this someting that we must also do?? (the US sensor baud rate is 9600, so we guess this is not a fast communication....)
Thank you in advance and sorry for the large post!
Not entirely sure, but I think there is a a serial console on port A that could conflict. Have you tried another port?
I leave 1-2 to answer by asctec, but I think it should work.
3 should not be necessary. If you set the clock frequency for fast operation though (e.g. To run asctec_mav_framework), make sure that you can still set the baudrate low enough (9600 / 8) for your US sensor.
From: "Xisco [via asctec-users]"
Date: Wednesday 27 May 2015 6:28
To: Markus Achtelik
Subject: Mastermind Serial ports and US range finder
Thank you for you answer.
We observe the same behavior using port A and B.
Regarding the baudrate issue, the Mastermind was bought as part of an special sale that included the AscTec Firefly + sFly Configuration . We have checked that, using this "sFly Configuration", the communication between the HLP and the Mastermind board (via UART_C, /dev/ttyS2) works fine (we make use of Asctec SDK + ROS). Our question now is whether the sFly Configuration includes the Mastermind Specific Setup for configuring the serial ports for fast communication, as explained in section 5.2 of http://wiki.ros.org/asctec_mav_framework/Tutorials/onboard_computer_setup. Does anybody know it??
If that's the case, that means that the clock frequency has been set for fast operation. What do we have to change to also allow slower communications like the one we need for the US sensor (baudrate 9600)??
Thank you in advance!!
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