ESP8266 Community Forum

- Fri Jul 17, 2020 4:33 pm #87942 Hi everyone,

I have been using the NodeMCU and Lua for a while to create monitoring nodes that communicate via MQTT. I have tried to add an SDS011 dust sensor to one of these nodes but I'm getting random exception resets of the NodeMCU that seem to be caused just by the serial connection being active. The SDS011 sends a message every second, I have tried the hardware and soft UART with the same result.
I have checked the specs for the SDS011 and the serial connection is 3.3v, so I don't think it should be anything physical.

Even with a stripped down script as below I am getting crashes, I have tested on several NodeMCUs with the same result.

Script:

Code: Select alllocal l_sds_data = ""

function sds_read(l_sds_data)
    print("sds_read "..node.heap())
end

s = softuart.setup(9600, 2, 3)

s:on("data", 10, sds_read)


The only way I found to keep the NodeMCU alive is to detect a soft reset and trigger an external reset, using the code below in init.lua. Without this hard reset the wifi would never reconnect. You can see the output of this code in the log further down.

Code: Select all-- Report on startup reason
rawcode, reason, exccause, epc1, epc2, epc3, excvaddr, depc = node.bootreason()
if reason == 0 then
    print("Power up")
elseif reason == 1 then
    print("Hardware watchdog")
elseif reason == 2 then
    print("Exception reset")
    print("EXCCAUSE "..exccause)
    print("EPC1 "..epc1)
    print("EPC2 "..epc2)
    print("EPC3 "..epc3)
    print("EXCVADDR "..excvaddr)
    print("DEPC "..depc)
    gpio.mode(6,gpio.OUTPUT,gpio.PULLUP)
    gpio.write(gpio.LOW)
elseif reason == 3 then
    print("Software watchdog")
elseif reason == 4 then
    print("Software restart")
elseif reason == 5 then
    print("Wake from deep sleep")
elseif reason == 6 then
    print("External reset")
end


Every few minutes it crashes as the log extract below:

Code: Select allsds_read 35088
sds_read 35088
sds_read 35088
sds_read 35088

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

load 0x40100000, len 27928, room 16
tail 8
chksum 0x8c
load 0x3ffe8000, len 2584, room 0
tail 8
chksum 0xf8
load 0x3ffe8a18, len 8, room 0
tail 8
chksum 0x12
csum 0x12
{‚Ÿâsä2’lŒ„ ìn~2cb„oàŽoäo~#Žƒ$ŽŽlònoŸŒonž 䛂’`~ƒ2„Nožì²œ¾{$~ƒc„noŸì’ƒ² „ãäƒoäÛr‚ûo|ìd$l c’œðŸ|r’dœnà‚nâ l`Œãr’lŒ$Œd`„âr²p‚äl„l Œãr“l¾Œl$`{lŽ‚b ŒŸÂcBì|ŒcprÜãÜbœplœ$ ìòNÎ2Nnâ $#lŒŽŒ€d$d$Žì„Œ€$rd€oü „¾"bl$ŽÛä#„¾BblŒcrl{
NodeMCU 3.0.0.0 built on nodemcu-build.com provided by frightanic.com
   branch: master
   commit: 8d091c476edf6ae2977a5f2a74bf5824d07d6183
   release: 3.0-master_20200610
   release DTS: 202006092026
   SSL: false
   build type: float
   LFS: 0x0 bytes total capacity
   modules: bme280,dht,file,gpio,i2c,mqtt,net,node,softuart,struct,tmr,u8g2,uart,wifi
 build 2020-07-06 17:40 powered by Lua 5.1.4 on SDK 3.0.1-dev(fce080e)
Exception reset
EXCCAUSE 0
EPC1 1076054560
EPC2 0
EPC3 0
EXCVADDR 1076341284
DEPCàrl $Üž| Œlà|Œlìb|‚䲟|"ŒpŒp~òoŸloNÜãìcpŒŽ$r$rlpòoàƒl#oã|„ìŽã„bŒònoïl„ l on$`orŽ›’nä’`pûoàr„ÜœãàbNâ|ŒÛŽ"Œònoïl`2Nn$`orŽÛ’nãl`pûoàr„ÜœÂlbNâ|"Œònoïl`nol Nr²Ÿî„l r’ÛNŒ$`rƒ’›oä2’lŒŒäo~cc„p2roäN~BŽpâ€r$ûon¾ „noŸì’ƒ² ‚2Œonž 䛂“`~ƒb„noŸì’ƒ’ Œãä‚Nì|rƒòN|ì$ll B’ß|r“$Üoàƒoã l ŒÂœn‚l„l2„l`Œãr“lä$„l`Œãr’l¾Œl$`rl‚sl„ßâ„"ì„bŒBprœÂãBÜp$Ül äûoïoNâ d#$ŒŽ„l$l$Žì„Œ€$Žs$€oü ŒžãŒ#ll’ìc„ßâ„blŒcrl{
NodeMCU 3.0.0.0 built on nodemcu-build.com provided by frightanic.com
   branch: master
   commit: 8d091c476edf6ae2977a5f2a74bf5824d07d6183
   release: 3.0-master_20200610
   release DTS: 202006092026
   SSL: false
   build type: float
   LFS: 0x0 bytes total capacity
   modules: bme280,dht,file,gpio,i2c,mqtt,net,node,softuart,struct,tmr,u8g2,uart,wifi
 build 2020-07-06 17:40 powered by Lua 5.1.4 on SDK 3.0.1-dev(fce080e)
External reset
Connecting to WiFi access point...
> Connection to AP(BTHub6-TPRH) established!
Waiting for IP address...
Wifi connection is ready! IP address is: 192.168.1.187
Startup will resume momentarily, you have 10 seconds to abort.
Waiting...
Running
sds_read 35072
sds_read 35072
sds_read 35072


I am using the Master branch of firmware from nodemcu-build.com

I have done some basic tests, such as unplugging the SDS011 connections, then I don't get any resets (or data of course).

Can anyone tell me where I am going wrong?

Thanks for any help you can offer!
Kris.