MAX13487E not receiving - Page 1
Forum section: electronics / projects

author: n4te
author_rank: Regular Contributor
timestamp: October 23, 2023, 08:11:23 pm
content: I'm trying to communicate between twoMAX13487E, which does half duplex RS485 with auto direction. Using a logic analyzer I see the data go into the first IC, come out as A/B, go into the second IC, but it doesn't come out.Sending side for this test:The A/B coming out of there looks good.Receiving side:My test point is at RO (U4 pin 1), but I don't see the data there.I tried with RE tied to 5V as shown (receiving enabled/disabled by auto direction). I also tried RE tied to GND (receiving always enabled). Still no data.I tried swapping A and B even though I'm sure they were right, still no data.I don't know what else to try. I don't want to give up on this IC, as it would require changing a bunch of designs. Any help or ideas are appreciated!

author: n4te
author_rank: Regular Contributor
timestamp: October 26, 2023, 12:52:16 am
content: Turns out the receiving ESP32 was using light sleep to run the loop slower and reduce current consumption. That shutdown the UART some of the time, resulting in some really wacky behavior. It was painful, but all is OK now.

author: HwAoRrDk
author_rank: Super Contributor
timestamp: October 26, 2023, 01:51:50 pm
content: I have nothing to add for the question at hand, but if you are a DipTrace user, then I have a couple of suggestions:- Use Net Port symbols for power rail connections rather than trailing unconnected net lines (or wireless net connections off a pin). There are also a variety of ground port symbols if you need to differentiate multiple grounds.- You can flip schematic symbols horizontally and vertically, so you could flip that MAX13487E symbol horizontally and not have the ugliness of net lines crossing the symbol.

author: n4te
author_rank: Regular Contributor
timestamp: October 26, 2023, 02:21:39 pm
content: Thanks! I really like DipTrace, most of the time.I got tired of hunting down power and GND symbols, so I started just ending the wire and showing the name to be faster. Also this is similar to a pin with an arrow, and I feel it's odd to use an arrow for a pin but something else for a wire. I'd really like to be able to end a wire with an arrow to the net name.I should really modify the MAX13487E symbol to have all the inputs on the left, so this is just me being lazy again. If I only flipped it then the outputs would be on the left.

author: HwAoRrDk
author_rank: Super Contributor
timestamp: October 26, 2023, 03:17:12 pm
content: Quote from: n4te on October 26, 2023, 02:21:39 pmWhat's hard to find?They're two clicks away: Components -> Net Ports (3rd category from top). If there isn't one for the exact thing you want (e.g. '1V5'), just pick any one and edit its name.You can use thePort_InandPort_Outsymbols for arrows. You can even use thePort_In#/Port_Out#symbols for KiCad-style arrows-with-net-name-inside if you change the part marking name alignment to 'Center'. Although that has it's own inconvenience of trying to pick one of the fixed-size arrows that will entirely contain your net name.Quote from: n4te on October 26, 2023, 02:21:39 pmWhat version of DipTrace are you using? I just looked up the MAX13487EESA+T component in the standard library, and it doesn't have the same symbol as you have. It's more sensible, with inputs on the left and A/B and power/ground on the right. I'm using 4.2.x.

author: n4te
author_rank: Regular Contributor
timestamp: October 26, 2023, 04:04:40 pm
content: I suppose you are right. The symbol is about as annoying to place and move around as the name text. I'd still prefer a wire ending in an arrow, looking just like the pin ending in an arrow.I'm using 4.3. I probably got the IC symbol from SnapEDA. Searching all the local libraries is slow and often I end up needing to find it on SnapEDA anyway, so sometimes I just skip the local libraries. Browsing them is unmanageable, I'm almost never able to guess which category to look in. You're right the symbol is much better, I'll switch to that!