5 replies to this topic

[Eng Yousef]

hi all i'm working on tracking project. i'm using 2 netduino (netduino 1) sends "hi" evry 1000ms by xbee... (netduino 2)reply "hi2"... when ever it pass 30 second (netduino 2) didn't recive "hi" from (netduino 1)... (netduino 2) gets the GPS information and send it by sms... So (Netduino 2) needs : 1- xbee serial port 2- GPS serial port 3- GSM serial port for sms can i use???? : 1- xbee serial port D0,D1 2- GPS serial port D2,D3 3- GSM serial port for sms D7,D8 i think the hard part is to deal with D7,D8. any idea how to read and write D7,D8 seial data???? thanks

[Chris Walker]

Hi eng, Netduino's pins D7/D8 are RTS/CTS (flow control for COM2), not another serial port. Chris

[Spork]

Netduino's pins D7/D8 are RTS/CTS (flow control for COM2), not another serial port.

This is a little late, but I wanted to post a correction: D7/D8 are supposed to be flow control for COM2. They don't function as such in 4.1 or 4.2. If anybody reading this thread cares about RTS/CTS, please comment and/or vote on the CodePlex issue, as it's still "unassigned" with no resolution in sight.

Thanks

[Chris Walker]

Thank you for the post, Spork. Just FYI, pins D7/D8 can be used for either RTS/CTS _or_ a third serial port on the Shield Base. Chris

[nakchak]

Depending on your project requirements a Maxim MAX3100E chip can work quite nicely as a 3rd UART or if you require a full RS232 implementation the MAX3111E will do the trick (the MAX3111E is a MAX3100 with an Integrated MAX232 for RS232 level conversion etc.) Both chips are available in DIP packages so dead easy to breadboard or solder, and only require a couple of caps and a crystal. They are SPI slave devices so 4 wires (5 if you want to make it interrupt based) and you have a fully featured 3rd serial port.

The only caveat i can add with regards to there use is that the CS line needs to be latched for it to work in as fast a manner as possible, other wise you have to loop through your byte array and send a byte at a time, this can be achieved with either a hardware latch, (Mario Vernari has an excellent article on this here or you need to modify the firmware to toggle the CS line, however once you do that you can get a reliable 256000 baud serial link going, but for most situation 9600 baud will suffice and that is easily achievable without any additional hardware or firmware mods.

[Spork]

Just FYI, pins D7/D8 can be used for either RTS/CTS _or_ a third serial port on the Shield Base.

So I read elsewhere, but I think the original post was w.r.t. the "plain old Netduino" (hereinafter "PON"). Still, the Netduino Go looks interesting, so I will almost certainly switch my application onto a Shield Base, once Ethernet and SD are available, and I guess that will finally end my RTS/CTS agony. Glad to see you guys working on new stuff.