AJB2K3 Posted March 17 Posted March 17 27 minutes ago, Toastie said: I am just too busy right now with work stuff - it is the second round of exams (you take when the first try, well, somehow "failed". Or you want to improve. Generally, people becoming increasingly nervous as they have only three tries ... which I hate, exams are good for almost nothing, but that is my very personal view. Best wishes, Thorsten I failed all my exams except for science. I resat my English and passed it 10 years after leaving school. Quote
Wapata Posted March 17 Posted March 17 23 hours ago, Gunners TekZone said: I also replaced ALL the ribbon cable (the remaining wires were just power and GND) to make it even more flexible to assemble. Cabling done. Serial null modem communication still one way only from computer to device. TTL still doesn't work. No more 9vLED flickering while moving the board. Quote
Toastie Posted March 17 Posted March 17 2 minutes ago, AJB2K3 said: I failed all my exams except for science. Well, if you were still enrolled, had visited my office, there were good chances I'd offered you a student job. Spoiler Then let you do some research, then pulled your hair to get the rest of the stuff assembled to pass the required exams, and then let you go nuts in the lab. I have never seen any transcript or scoresheet or GPA sheet or whatever "The System" produces, when students inquired about chances to joining my group: We made an appointment and talked to each other. As long as it takes. In the end, I had to decide of course, but this was not a "No" or "Yes", it was the result of a respectful and at eye level conversation. It always worked, for more than 30 years now. Oh, and it still works. Crazy, isn't it: Talking at eye level, having AI or stiff score levels (with 50% you pass ^^), still vastly outperforms any other means for assessing whether joining a research group makes some sense for all involved. All the best Thorsten 4 minutes ago, Wapata said: TTL still doesn't work. Dam-ned. OK, I broke out my notebooks, the type with pages, I scribbled on. So what I did (apparently 2025-2-18, and man, I should improve my writing) is: Took a Ser2TTL adapter (w/o USB power supply port), wired the four lines VCC, RxD, TxD, and GND to an HC-05 BT2TTL adapter (1:1 = null modem). The RxD line, as the HC-05 is 3.3V, the Ser2TTL is 5V, using a 1kOhm resistor for safety reasons. Then used a 78L05 regulator to tap into the regulated 9V rail of the Interface B and provided the HC-05/Ser2TTL adapter with 5V. GND of the 9V Interface B supply = GND of the adapters. Best wishes Thorsten Quote
Wapata Posted March 17 Posted March 17 (edited) Thank you for taking a look. For what is see from dangerous testing here is that the grounding is an issue : if i swap my Rx/Tx wires WITHOUT ground, both Rx/Tx led activate on the arduino. If I put arduino ground to big ground of Interface-B then I can have the red light go off now. If i take back ground to SUB9 ground it doesn't work at all anymore. So the IS something about groundS. ... and it seem it's not wire lenght EDIT By the power of NO fun ! If I disconnect the usb cable and put it back I can make everything work first try with the big Ground and if i do the same with sub9 ground it doesn't work Hurray ? EDIT So it's not cable length. So i cannot use my plan to use the DB9 connector without compromissions now. Edited March 17 by Wapata Quote
Wapata Posted March 17 Posted March 17 It's a strap So it work with grounds merged (i hope it's okay) ONCE with LEGOInterfaceB. I can click on the Stop button on the device and resume, but i can't click on the Stop button on the computer and resume. We will see what it does with a real TTL-USB thing. Thanks for your support ! Quote
Wapata Posted March 18 Posted March 18 The upper GND as pictured before is the big Ground. I've noted too that someone put a component to make 5v but i thing there is already 5v on the board... in this upper left corner. I have to take a second look to put the Interface-B on Bluetooth One day... After playing with the device... I still have the SUB9 serial port yes. I case i found my mini oscilloscope and can rework on the "where does the signal get lost" part. But I can't "see" if the signal is clean or not. More important : I will use the SUB9 port to "clamp" the final TTL-USB device. Quote
Wapata Posted March 18 Posted March 18 I've found back my oscilloscope ! Look at "dso shell" on google image. It was on the "measurement tools drawer"... how am i supposed to find it here... So for serial communication, if you tell me what to look for, i can trace where the signal get lost (if it is fun for you too ! in the end i already have a working device). Quote
Wapata Posted March 18 Posted March 18 Mine doesn't either. But I am able to put the interface-B in a normal running mode by using the TTL. Soooo I may use an other Arduino mega, a serial monitor and... How do I translate to text ? I guess it should be TTL at the left of the two white square component and serial at the right of them so... Not the same voltages ? Quote
Wapata Posted March 18 Posted March 18 Oh... I was thinking that serial and null modem use 12v for the 1 and 0v for the 0 but the TTL 5v for the 1... Crap, I didn't take a second look on that and I may be wrong Quote
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