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Topic: Floating serial issue [SOLVED] (Read 355 times) previous topic - next topic

guy_c

Aug 24, 2019, 08:52 pm Last Edit: Aug 26, 2019, 09:55 pm by guy_c
Hello, i have a master board sending commands to a slave board via serial 2. When master is loaded with new code, slave receives plenty of nonsense. Any elegant way, avoiding pulldowns, to avoid this nuisance? Thanks

Solution
on the slave board, setup section, add after (or before)
  Serial2.begin(115200);// ~100us/char
the line
  pinMode(RX2_PIN, INPUT_PULLUP);
with RX2_PIN correctly mapped

TheMemberFormerlyKnownAsAWOL

Quote
Any elegant way, avoiding pulldowns, to avoid this nuisance?
Post your code, post your schematic.

It is a nuisance, isn't it?

raschemmel

#2
Aug 24, 2019, 08:56 pm Last Edit: Aug 24, 2019, 08:57 pm by raschemmel
You really haven't provided any useful information or schematic.
If you want help you have to start at the beginning and explain EVERYTHING and include a schematic
if possible.

@HAL9000,
What happened ? Did you max out the post counter ?
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

TomGeorge

Hi,
Have you got the gnds of the  two controllers connected?
What model Arduinos are you using?

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

guy_c

Hi,
Have you got the gnds of the  two controllers connected?
What model Arduinos are you using?

Thanks.. Tom.. :)
Thank YOU Tom,
Both are mega board sitting by solderless cards, both (mega and solderless) mounted on a plastic support platform from sparkfun
Yes the two board's grounds are connected.

Again, issue is while master is undergoing code download. In this situation, there is noise AND outputs (master Tx) are (i think) threestated.

TomGeorge

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom.. :)
Everything runs on smoke, let the smoke out, it stops running....

Idahowalker

Hello, i have a master board sending commands to a slave board via serial 2. When master is loaded with new code, slave receives plenty of nonsense. Any elegant way, avoiding pulldowns, to avoid this nuisance? Thanks
You may try using a GPIO from the master connected to the slave as a ValidMasterSignal and monitor that signal, at the slave end, for MasterIsValid and from there do the blah and blah and blah thing.

guy_c

Hi,

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks.. Tom.. :)

TheMemberFormerlyKnownAsAWOL

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

jremington

#9
Aug 25, 2019, 06:00 pm Last Edit: Aug 25, 2019, 06:03 pm by jremington
Image of OP's rat's nest, posted properly. Note the area circled in RED!



Is the white wire making a good, secure connection?

guy_c

You may try using a GPIO from the master connected to the slave as a ValidMasterSignal and monitor that signal, at the slave end, for MasterIsValid and from there do the blah and blah and blah thing.
Any *elegant* way...

Idahowalker

@guy_c, have you considered how much current is drawn through your bread board vs how much current a breadboard connection can supply?

TomGeorge

#12
Aug 25, 2019, 11:19 pm Last Edit: Aug 25, 2019, 11:25 pm by TomGeorge
Thank YOU Tom,
Both are mega board sitting by solderless cards, both (mega and solderless) mounted on a plastic support platform from sparkfun
Yes the two board's grounds are connected.

Again, issue is while master is undergoing code download. In this situation, there is noise AND outputs (master Tx) are (i think) threestated.

So if you are not downloading code, you have no noise?
That is, when everything is loaded, and running, you have no noise?
While downloading code, turn the other controller OFF.

Trying to run any controller while downloading code to it will usually end in problems?

Sorry for the umteenth time, can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
This is a very important part of troubleshooting.

Tom.... :)
Everything runs on smoke, let the smoke out, it stops running....

raschemmel

Tx & Rx cannot be used for interfacing while code is being downloaded because those pins are used for code download. You need to remove the connections to Tx and Rx before downloading code and then you can reconnect them after the code is downloaded.

Post your code so we can see what lines you are using .
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

guy_c

Tx & Rx cannot be used for interfacing while code is being downloaded because those pins are used for code download. You need to remove the connections to Tx and Rx before downloading code and then you can reconnect them after the code is downloaded.

Post your code so we can see what lines you are using .
Tx2 is being used during download? Can you please post a link to this data?

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