Does the current indicator show some current? If not, you would be without short circuit protection...
I installed JMRI. I am getting a number on the current meter and I am able to read CVs from the decoder. Looks like Im set!!!!
BTW, I like the LMD18200 H bridges so much that I replaced the "standard" motor shield by breakout boards with them: - the chip can be obtained at eBay for 4$ now (not 20$ anymore as KE4NYV mentioned) - yes, 3A continous current! - minimum number of discrete components around needed. DIR signal for second half of H bridge is inverted internally. Current sensing resistors have "comfortable" value 4.3kOhm, unlike the L298N ...(0.15 Ohm) - 5V not needed. Just the bridge supply voltage. - they switch fast > minimum phase distortion of the DCC signal. Decoders might like this. - they provide thermal overheat flag signal Still does not look interesting?
Not a big deal. I used two modules purchased from China. Above the WiFi router is Arduino Mega with Ethernet shield, above it two modules connected by 7 wires. As you can see the right module is not used yet since I do not have the programming track yet. The orange bumpers for Arduino and the modules are printed at 3D printer.
When using the current sensing resistors about 4.4 kOhm no code modification is necessary except it is reasonable to change the CURRENT_SAMPLE_MAX value as recommended by Gregg here: Introducing DCC++ ---a complete open-source DCC station and interface The 7 wires are (in case of Arduino Mega): common ground Mega pin 3 (Signal Enable Main) - LMD_Main pin PWM Mega pin 12 (Direction Main) - LMD_Main pin DIR Mega pin A0 (Current Monitor Main) - LMD_Main pin Current Sense Mega pin 11 (Signal Enable Prog) - LMD_Prog pin PWM Mega pin 2 (Direction Prog) - LMD_Prog pin DIR Mega pin A1 (Current Monitor Prog) - LMD_Prog pin Current Sence
One of the issues with those parts is that they are nearing End-of-Life, meaning they won't be manufactured for much longer. Designing a new product with soon to be obsolete parts isn't a good idea.....maybe that's why the parts are now available at a lower cost???
Can you please let me know where you find this info? At the TI vendor's webpage I see status ACTIVE: recommended for new designs.
New to the forum, I enjoy working with Arduino, and I came across DCC++. it renewed my interest in trains. unfortunately all I have is some old atlas brass track, and an Athearn GP38-2 (2009) that I recently found was not even close to DCC compatible. but the interest is still strong (the wallet however is a little weak). I have DCC++ loaded on an UNO with a L298 clone from SeedStudio, I think. I can control it via JMRI, though it doesn't really affect much, other than my oscilloscope. I really have no idea if it really works. I see some motor controllers need jumper wires to adapt them. is that an issue with a 298? ~Travis
Found my motor shield was defective. figures now, if I made my own H-Bridge, like attached Eagle Schematic , would it work with DCC++? J1 is the Input connector (1, 2, 3 --> Gnd, Enable, DCC), and J2 is the track output. I would need two of these, obviously. but if I connect it so SIGNAL_ENABLE_PIN_* connects to the Enable pin, and DCC_SIGNAL_PIN_* connects to the DCC pin. if it will work, then I just have to find the correct MOSFETs to suit the project. ~Travis
I don't see an external power supply connection on the schematic. This would be required to allow you to exceed the power limits of the Arduino.
common ground, and VCC (I didn't find the right symbol in the few minutes I drew it in) goes to the external power supply. Sorry, I should have explained that. ~Travis
well... after a little more research, my H-Bridge is wrong. maybe I will just buy an H-Bridge, and save myself from burning up MOSFETs from shoot-through current during switching. oh, well. you win some, you lose some. But on the plus side, I found a sight detailing how to convert my Athearn GP38-2 to DCC. ~Travis
