LoPy serial stops after a few seconds

[ekwus]

Hi

I have just received my LoPy and got it hooked up via a USB-to-Serial adaptor on a breadboard (No Expansion Board).

I have managed to upgrade the firmware to 1.6.12.b1 and can get serial comms using Putty on COM4.

However, after a few seconds the serial port stops responding. This seems to vary between 10 seconds and about 1min. When this happens the Blue flashing LED also stops flashing and is off until I reboot the board.

I also can't connect to the WiFi from my NUC but not sure if that is related or not.

Has anyone else seen this? Do you think I have a faulty board?

Cheers

Dave

[TravisT]

Yep,
Put a 10k and a 0.01uF on the RST to 3.3v and see almost no noise now on the RST pin.

Went form running for less than 30 seconds to... well it just seems to keep working now.

I am pretty sure the is the same issue, wanted to post to help people like myself in the future.

[TravisT]

I am using some Wipy modules on a custom board and found that if I solder them directly to the board I have minimal issues, but if I use header more than 50% of the boards randomly turn stop.

It would be nice to have this more explicit that a pull up and probably a cap is needed for reliable operation. These issues cause negative views of the product.

I would heavily suggest in the documentation for each development hardware use guide with suggested supporting electronics.

[Eduardo]

@ekwus THANKS

[robert-hh]

@eduardorocha Do you run with or without expansion board.
If not: the expansion board has a 100k pull-up resistor at reset. That may be missing.
If yes: Check the quality of your 5V supply. Even if the xPy has a built-in regulator, it cannot cope with a really bad supply.

[ekwus]

@eduardorocha have you tried a pull-up resistor between the Reset pin (first pin on side and beR the Reset button)?

Any reasonably high resistor say 10K between that pin and the 3.3V output pin (3rd pin in on other side) should stop the noise causing a reset.

The expansion board must have this or the ground sheilding is enough. Not sure why the Reset button circuit doesn't​ do this for us - can anyone explain?

Cheers

Dave

[eduardorocha]

I have this same problem, but only when feeding externally with 5V.

This problem does not occur on the expansion card.

Anyone have any idea how to solve it?

[ekwus]

Turns out I was needing a pull-up resistor on the Reset pin - my guess is that noise from the serial pins was enough to cause a reset during the firmware update.

There doesn't seem to be much documentation on the requirements for using the boards beyond the expansion board.

Thanks for everyone's help.

Cheers

Dave

[ekwus]

Hey

I managed to capture a core dump from the faulty unit as below. Not sure if this is the same issue or not.

I upgraded my second board which had ran overnight with serial and WiFi connected and without any problems. Now it is behaving the same as the first.

Looks like it is an issue with the new firmware. Has anyone else got issues with 1.6.12.b1 firmware for the LoPy?

Cheers

Dave

ets Jun 8 2016 00:22:57

rst:0x1 (POWERON_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
ets Jun 8 2016 00:22:57

rst:0x10 (RTCWDT_RTC_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0x00
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:QIO, clock div:2
load:0x3fff9010,len:8
load:0x3fff9018,len:248
load:0x40078000,len:4056
load:0x4009fc00,len:920
entry 0x4009fde4
I (13248) wifi: wifi firmware version: 90b1b8b
I (13248) wifi: config NVS flash: disabled
I (13248) wifi: config nano formating: disabled
I (13264) wifi: Init dynamic tx buffer num: 32
I (13264) wifi: wifi driver task: 3ffd6360, prio:23, stack:3584
I (13264) wifi: Init static rx buffer num: 10
I (13267) wifi: Init dynamic rx buffer num: 0
I (13271) wifi: Init rx ampdu len mblock:7
I (13275) wifi: Init lldesc rx ampdu entry mblock:4
I (13279) wifi: wifi power manager task: 0x3ffdb71c prio: 21 stack: 2560
I (13286) wifi: sleep disable
I (14275) wifi: wifi timer task: 3ffdc7b0, prio:22, stack:3584
I (14327) wifi: Init ampdu: 0
I (14327) wifi: mode : softAP (24:0a:c4:00:ee:27)
MicroPython v1.8.6-593-g8e4ed0fa on 2017-04-12; LoPy with ESP32
Type "help()" for more information.

import os
os.uname()
(sysname='LoPy', nodename='LoPy', release='1.6.12.b1', version='v1.8.6-593-g8e4ed0fa on 2017-04-12', machine='LoPy with ESP32', lorawan='1.0.0')

os.uname()
(sysname='LoPy', nodename='LoPy', release='1.6.12.b1', version='v1.8.6-593-g8e4ed0fa on 2017-04-12', machine='LoPy with ESP32', lorawan='1.0.0')

▒▒▒▒▒▒▒▒▒`tion Error of type IllegalInstruction occurred on core 0. Exception was unhandled.
Register dump:
PC : 0x4008uuMdtto rror of type StoreProhibited occurred on core 0. Exception was unhandled.
Register dump:
PC : 0x40087eb5 PS : 0x00060033 A0 : 0x80087ef6 A1 : 0x3ffb58b0
A2 : 0x00000036 A3 : 0x0004c000 A4 : 0x80081814 A5 : 0x3ffb4f80
A6 : 0x000eda12 A7 : 0x00000000 A8 : 0x0000007d A9 : 0x0000007d
A10 : 0x0000002a A11 : 0x3ffb5ad0 A12 : 0x00000000 A13 : 0x3ffb5ac0
A14 : 0x00000000 A15 : 0x00000000 SAR : 0x00000020 EXCCAUSE: 0x0000001d
EXCVADDR: 0x80087f1e LBEG : 0x4000c2e0 LEND : 0x4000c2f6 LCOUNT : 0x00000000

Backtrace: 0x40087eb5:0x3ffb58b0 0x40087ef6:0x3ffb58d0 0x40088137:0x3ffb58f0 0x400882e3:0x3ffb5970 0x40081145:0x3ffb5990 0x40086000:0x3ffb5a50 0x40086000:0x3ffb5a70 0x400870a1:0x3ffb5a90 0x40087197:0x3ffb5ac0

================= CORE DUMP START =================
Removed as it was flagged as SPAM
================= CORE DUMP END =================
Rebooting...
ets Jun 8 2016 00:22:57

rst:0xc (SW_CPU_RESET),boot:0x13 (SPI_FAST_FLASH_BOOT)
configsip: 0, SPIWP:0x00
clk_drv:0x00,q_drv:0x00,d_drv:0x00,cs0_drv:0x00,hd_drv:0x00,wp_drv:0x00
mode:QIO, clock div:2
load:0x3fff9010,len:8
load:0x3fff9018,len:248
load:0x40078000,len:4056
load:0x4009fc00,len:920
entry 0x4009fde4
I (1688) wifi: wifi firmware version: 90b1b8b
I (1688) wifi: config NVS flash: disabled
I (1688) wifi: config nano formating: disabled
I (1704) wifi: Init dynamic tx buffer num: 32
I (1704) wifi: wifi driver task: 3ffd6360, prio:23, stack:3584
I (1704) wifi: Init static rx buffer num: 10
I (1706) wifi: Init dynamic rx buffer num: 0
I (1710) wifi: Init rx ampdu len mblock:7
I (1714) wifi: Init lldesc rx ampdu entry mblock:4
I (1718) wifi: wifi power manager task: 0x3ffdb71c prio: 21 stack: 2560
I (1725) wifi: sleep disable
I (2714) wifi: wifi timer task: 3ffdc7b0, prio:22, stack:3584
I (2743) wifi: Init ampdu: 0
I (2744) wifi: mode : softAP (24:0a:c4:00:ee:27)
MicroPython v1.8.6-593-g8e4ed0fa on 2017-04-12; LoPy with ESP32
Type "help()" for more information.

[ekwus]

Hey

Ok I decided to power up the second LoPy I ordered at the same time. Plugging it directly in to the same position in the breadboard with the same connections.

It has powered up and I can talk to it over serial and connect to it using WiFi and even see the boot.py and main.py files over FTP.

The only step I skipped was to update it to the latest firmware.

The question now is; was it a faulty unit or is the latest firmware to blame?

I tried to boot the "faulty" unit to factory using P12 to 3.3V for 7-9 seconds but it has all the same problems and os.uname() reports the latest firmware version so I don't hink it is working as expected.

Cheers

Dave

[ekwus]

Thanks for the up votes :-) @livius @guy

[livius]

@ekwus

I can only post every 10 minutes as a newbie :-)

I have upvoted your post and you can now post faster

[ekwus]

Hey @jmarcelino @lebucur Yeah Power Supply, LoPy and Serial-to-USB GND are connected together. Sorry I was going on to post this in the other comment but I can only post every 10 minutes as a newbie :-)

I've also since, disconnected Serial and just powered up the LoPy. The LED flashes blue and I can see the SSID but it stops flashing and the SSID disappears in the same manner as before - so I don't think it is directly related to serial.

I have another LoPy here that is still in the box but I'm reluctant to power it on at this point until I know it is not me that is causing the problem. Note: I don't have a LoRa antenna attached but I was thinking the warning about that would be when actually enabling LoRa. Ordering antenna and Expansion board today as it was an oversight really.

Cheers

Dave

[jmarcelino]

@ekwus
And your LoPy GND pin is connected to both your power supply and GND on your USB-Serial, as @lebucur was saying?

[ekwus]

@jmarcelino Hey, nothing extra on the serial port, just stops responding and the bench supply current limit is turned up to max - it is a 10A supply that I have used to supply high power LED strings in the past so should be working.

I checked and there is only the 1 GND pin too.

Cheers

[lebucur]

@ekwus I also connect the GND of my USB-to-Serial converter.

[jmarcelino]

@ekwus
Nothing, errors or strange characters, appears in the com terminal right?

Is the power supply current limited in any way? While the average may appear like 30mA, the ESP32 can frequently draw >150mA peaks when WiFi is operating

[livius]

@ekwus
I saw something like this few times in current firmware - but i then have not connected COM and do not see what happend before - i add something to wish list
https://forum.pycom.io/post/6876

[ekwus]

@jmarcelino I am providing 5V via the Vin pin and Gnd on the pin next to it from a bench supply.

The current meter shows around 10 to 30 mA usage.

Just had a thought that maybe there are other Gnd pins that need connecting.

Cheers

Dave

[jmarcelino]

@ekwus
How are you powering the LoPy?