config settings for ESP and ublox cellular communication about ubxlib HOT 12 CLOSED

The ESP32 is capable of using any pins with any HW UART block so it's really up to you; you could leave it at 1 or try changing it to 2, it shouldn't matter.

On the APN it is the same field you modify, you just put in it whatever string your SIM/service provider tells you to. I doubt that AT&T needs a specific APN though, the AT&T network should provide the necessary APN to the module at network registration and you should be able to leave the APN for that case at the default of NULL.

from ubxlib.

Hi Rob,

How is it going?

Yes, RTS and DTR are connected to GND in Sparkfun shield, I did a continuity check to board's GND with Voltmeter.

The Arduino Terminal report;

U_CELL_PWR: powering on.
AT
AT
AT
AT
AT
AT
AT
AT
AT
AT
U_CELL_PWR: powering on.
AT
AT
AT
AT
AT
AT
AT
AT
AT
AT
Added network with handle -7.
Bringing up the network...
Network is not available!
1 Tests 1 Failures 0 Ignored

My board is an Adafruit ESP feature board,
https://cdn-learn.adafruit.com/downloads/pdf/adafruit-feather-huzzah-esp8266.pdf

so I connect feather board gpio 16 which is RX2 to Sara R4 RXD pin, and its gpio 17 which is TX2 to Sara R4 TXD pin.
And in arduino src folder I modify the code to
define U_CFG_APP_PIN_CELL_TXD 17
define U_CFG_APP_PIN_CELL_RXD 16

So I guess 16 means gpio 16 and 17 gpio17, as I changed them to their esp32 pin 27 and 28 (ESP wroom pin numbers), got an uart error in the terminal, so I brought it back to 16 and 17 as seen above.

I swap the rx tx cables, it will have the same terminal report; Network is not available!

To be able to make the Sparkfun LTE modem working when I was connecting it to Arduino uno Redboard, setting MNO_ATT was important as follows;
IN Sparkfun code line 57;
https://github.com/sparkfun/SparkFun_LTE_Shield_Arduino_Library/blob/master/examples/Network_Info/Network_Info.ino
in order to have "LTE shield connected", I had to set
const mobile_network_operator_t MOBILE_NETWORK_OPERATOR = MNO_ATT
and
const String APN = "hologram";

To do the same thing In the ublox arduino code for feather board, in config part I set;
NULL, /* SIM pin, must be NULL /
"hologram", / APN: NULL to accept default. If using a Thingstream SIM enter "tsiot" here */

OR

I set it as
NULL, /* SIM pin, must be NULL /
"MNO_ATT", / APN: NULL to accept default. If using a Thingstream SIM enter "tsiot" here */

I set both to NULL, it does not work, unfortunately.

I wanted to see which pins you connect to rx and tx in devkit c;
https://github.com/u-blox/ubxlib/blob/preview_feature_arduino_updated/port/platform/common/automation/DATABASE.md

These are U_CFG_TEST pins (which I did not touch test pin configs) not U_CFG_APP pins, also in your ESP32;
U_CFG_TEST_UART_B=1 U_CFG_TEST_PIN_UART_A_CTS=-1 U_CFG_TEST_PIN_UART_A_RTS=-1 U_CFG_TEST_PIN_UART_A_RXD=26 U_CFG_TEST_PIN_UART_B_TXD=27 U_CFG_TEST_PIN_UART_B_RXD=14

Also in u_cfg_app_platform_specific.h You connect tx and rx as follows;
define U_CFG_APP_PIN_CELL_TXD 4
define U_CFG_APP_PIN_CELL_RXD 15
I do not understand why you connected tx and rx to gpio4 and gpio 15 or pin 4 or 15 of ESP32 devkit C
Because these are not uart pins of ESP32 devkit;
https://randomnerdtutorials.com/getting-started-with-esp32/

Thanks,
MoZen

from ubxlib.

The problem we have here, MCU UART apparently transmitting commands to the module but getting no response at all from the module, is likely due to one of the following reasons:

• no power supplied to cellular module [I assume you've checked this],
• cellular module is not powering-up [see below],
• transmit or receive UART lines are somehow not connected [you've checked this I think],
• UART flow control line (RTS) is telling the cellular module not to send data [you've checked this],
• baud rate is wrong [I guess this is unchanged from the default of 115200 which will work with all u-blox modules],
• IO voltages are wrong: please confirm that the UART lines at the cellular module are 1.8V logic, not 3.3V logic (e.g. for the standard ESP32 devkit C a level shifter would be required).

I've checked the integration manual for SARA-R4 and on page 20 it says: "Once a valid VCC supply is applied to the SARA-R4 series modules, they remain switched off in the power-off mode. Then the proper toggling of the PWR_ON/PWR_CTRL input line is necessary to trigger the switch-on routine of the modules that subsequently enter the active mode".

So the SARA-R4 series modules will NOT power on without a pin from the MCU being connected to the PWR_ON pin of the cellular module and the U_CFG_APP_PIN_CELL_PWR_ON in u_cfg_app_platform_specific.h being set to that MCU pin. The ubxlib code will then toggle that pin in the correct way to wake the module up.

Concerning the UART pins we use on ESP32 devkit C, it doesn't matter which lines are chosen: the UART HW inside the ESP32 chip can be muxed to any IO line on the chip (with a small number of exceptions); Espressif happened to label some pins of their IO connector as the UART pins but there is nothing special about those pins, they are just 3.3V digital inputs or outputs.

You can ignore the U_CFG_TEST_ pins, those are for if you are running our ubxlib tests, where we run UARTs back to back etc. on the MCU itself, they are in no way connected to the operation with a cellular module.

from ubxlib.

Progress, excellent. I would guess that the Hologram website showing a connection means that they have some form of back-door connection into the cellular operator and that the cellular module has powered up and registered with the network (which it will do automagically when a SIM is inserted). This is a good step forward, we have a PWR_ON connection, but clearly there is absolutely no communication yet between the module and your MCU. I guess that the blue LED you see blinking is connected to the module status pin, which matches what the Hologram website is already telling you but doesn't say anything about the [lack of] serial communications.

Did you check the IO voltages: remember that your MCU will be 3.3V logic, the module is 1.8V logic so without a level shifter somewhere the serial port will not work and the module may be damaged by over-voltage.

Setting the MNO profile is supported by ubxlib with the function uCellCfgSetMnoProfile(). You would simply add a call to that function, with networkHandle and your desired MNO profile number, between the uNetworkAdd() and the uNetworkUp() calls in the Arduino example, e.g. uCellCfgSetMnoProfile(networkHandle, 2);.

But none of that is going to do anything until the UART issue is resolved of course.

EDIT: just checked the image you posted in the other thread and there appears to be no level shifter in the UART lines between the MCU and the Sparkfun board so, unless there is one hiding on the Sparkfun board, this is definitely your issue; you need a bi-directional level shifter, e.g. one of these with the low-voltage supply for it connected to the VINT pin of the cellular module (which will supply 1.8V) and the high-voltage supply for it connected to the 3V3 pin on the ESP32 board.

from ubxlib.

Hmm, that's all fine then. One more thing to check: do make sure that the cellular module does NOT detect that the USB interface is connected to it; if it does it will ignore anything on the UART port. In other words JP6 must be open (and, while we're at it, JP4 and JP5 must be closed).

After that I'm out of ideas, I can't see any reason why the UART comms between the MCU and the cellular module never work. Time to get your Salaea probe or whatever out and monitor those UART lines.

from ubxlib.

Thanks Rob!

Yes, Sparkfun LTE board has many connection scenarios (Uart, Uno, USB). Yesterday, I designed a prototype for a SaraR4 breakout board to communicate with ESP directly(not using the Sparkfun shield), it has more direct pins from ESP to the breakout board; power-on, etc. This experience, Arduino-based ublox library, and your recommendations gave me the confidence to design the board, I will report how it works when ready!

Thanks,
MoZen

from ubxlib.

Hi again, and thanks for raising this as a separate issue.

There are a number of things you need to be concerned with in the cellular section of u_cfg_app_platform_specific.h. I will go through them one by one.

U_CFG_APP_CELL_UART: this is not a pin, it identifies the UART HW block inside your MCU which ubxlib should use for its UART interface. Without this there can be no communication with the cellular module, so it should not be set to -1 if you are using a cellular module. ESP-IDF by default uses UART HW block 0 for debug prints and so we by default use UART HW block 1 for our communications with the cellular module. This value doesn't usually need to be changed, you should leave it at 1 unless you are using UART HW block 1 for something else.

U_CFG_APP_PIN_CELL_ENABLE_POWER: if you have a relay or some such gating power to the cellular module then you need to set this to the MCU pin which controls that relay. If you don't you should set this to -1.

U_CFG_APP_PIN_CELL_PWR_ON: the cellular module has a pin named PWR_ON which may be connected to one of your MCU pins. PWR_ON tells the cellular module to power on and to power off again. If it is connected to one of your MCU pins then you must set the value of U_CFG_APP_PIN_CELL_PWR_ON to match. If it is not connected (i.e. you are relying on the cellular module just powering up when power is initially applied, which I believe most of them do) then set the value of U_CFG_APP_PIN_CELL_PWR_ON to -1.

U_CFG_APP_PIN_CELL_VINT: the cellular module has an output pin, named VInt, which supplies 1.8V for interface circuitry (noting that all u-blox modules are 1.8V IO, not 3.3V). If this pin is connected to your MCU then ubxlib can use it to detect that the module is powered-up. So please either set U_CFG_APP_PIN_CELL_VINT to the pin of your MCU that is connected across to the VInt pin of the cellular module or, if there is no such connection, set it to -1; ubxlib will work with or without this connection but this #define MUST be set to -1 if there is NO SUCH connection.

U_CFG_APP_PIN_CELL_TXD and U_CFG_APP_PIN_CELL_RXD: these I think you have understood.

U_CFG_APP_PIN_CELL_CTS and U_CFG_APP_PIN_CELL_RTS: from what you have said above you have not connected the UART flow control lines between the MCU and your cellular module, in which case please make sure to set both of these values to -1 or no UART communication will succeed.

If you need to set the APN, i.e. your SIM card/provider requires you to use a specific APN and not just accept the network default, then, for the sockets example, you need to look at the config structure. You will see that there is a comment against one of the fields /* APN: NULL to accept default. If using a Thingstream SIM enter "tsiot" here */; this is the field where you would enter your APN for this example.

from ubxlib.

Thanks, Rob,

Yes, I was suspicious U_CFG_APP_CELL_UART 1 has a more important role being at the top of the code, that is why I set it to 1 previously, but thanks for the clarification about it and other pins, I knew some of them reading the Sara-r4 datasheet and I had set most of the pins as you mentioned.

As you mentioned ESP32 has several uarts(3 I guess), Since I am using feather board(esp wroom-32) and one of its available uart pins; gpio 16 and 17 are u2rxd and u2txd, so is it uart hardware block 2? then should I set U_CFG_APP_CELL_UART to be 2?

APN in my case is hologram, so I will modify NULL in NULL, /* APN: NULL to accept default
But for setting let's say AT&T, which one should I modify?

Thanks,
MoZen

from ubxlib.

Hi Rob,

Thank you for your precious feedbacks,

I was able to upload the sockets.ino to ESP board; in the terminal after showing a few lines of AT, it says the cellular network does not connect, and the on Sparkfun Sara R4 breakout board that I power with a Lipo does not turn blue, I loaded code on Adafruit ESP feather also ESP dev board, same results...

Config setting; I directly manipulate u_cfg_app_platform_specific.h in Arduino libraries>src folder as follows;
// specify ublox module as Sarar4102B
define U_CFG_TEST_CELL_MODULE_TYPE U_CELL_MODULE_TYPE_SARA_R410M_02B

First Everything on u-cfg-short-range I set to -1
Then U_CFG_APP_CELL_UART 1
U_CFG_APP_PIN_CELL_ENABLE_POWER -1
U_CFG_APP_PIN_CELL_PWR_ON -1
U_CFG_APP_PIN_CELL_VINT -1
U_CFG_APP_PIN_CELL_TXD 17
U_CFG_APP_PIN_CELL_RXD 16
U_CFG_APP_PIN_CELL_CTS -1
U_CFG_APP_PIN_CELL_RTS -1
Lastly everything on U_CFG_APP_GNSS_UART is -1
I did not change any other .h files.

in Arduino code, I left "simpin" and APN to NULL,

I am using these pins on Sara-R4 breakout boards; In this video, Jim explains at minute 1:01 you can use it directly with uart;
https://www.youtube.com/watch?v=Eb6Ld0QAdj4&t=2s
similarly I am connecting to these uart pins.

Also you can find it in "UART interface" title here; https://learn.sparkfun.com/tutorials/lte-cat-m1nb-iot-shield-hookup-guide/all#hardware-overview

So the uart serial shown in the video has 6 pins, 2 NC, TX(I connected to Esp gpio17), RX(esp gpio17), Ioref(I connected to 3.3V on esp32 that will convert esp uart to 1.8 volts for sarar4 if you look at their schematic), and Gnd(I connected to feather esp grnd),

my question is

1. should I use a parallel pull-down resistor, a let's say 5K resistor to gnd on tx and rx pins between esp and sparkfun shield?
2. how can we increase the time it sends AT commands to the board, I guess I need to increase x here; int32_t x = 3; x >= 0; x--
3. we bought 10 sara-r410 chips, if sparkfun does not work with esp, do you have a breakout board eagle file for sarar4 so that we use its schematic for designing our prototype board?
4. Have you tested this sockets code with USA networks(AT&T,...)? because in the sparkfun hookup guide and from my experience it takes time until the network is connected(30 sec to 3 minutes), but in sockets.ino code it sends AT for I say 10 seconds and gives up.

Thanks,
MoZen

from ubxlib.

You say "in the terminal after showing a few lines of AT": would you be able to post what you see here, just so that I can understand what is happening better?

What you have set in u_cfg_app_platform_specific.h seems sensible.

On the pins etc, can you confirm that you have pin 17 of your MCU connected to the TXD input line of the module and pin 16 of your MCU connected to the RXD output line of the module (i.e. the module uses the DCE convention, so the TXD line of the module is the input and the RXD line of the module is the output). You will also, of course, need to make sure that the RTS line of the module is tied low (otherwise it will never send you anything) and you will also need to make sure that the DTR line of the module is tied low as, on SARA-R4 modules (see the bottom of page 35 of the SARA-R4 system integration manual) that is used as a way of controlling whether the module sends unsolicited result codes and we MUST have those or things will fail later on.

I'm not a HW engineer (despite having a degree in it, from many years ago) but I very much doubt that any pull-up or pull-down resistors are required on the TXD or RXD lines, that would adversely affect the dynamic operation of those lines.

You should not need to make any changes in the ubxlib code; anything that we think should be configurable (time-outs etc.) are brought out as conditional compilation flags you can tweak but lets not do anything like that yet, there is not yet any reason to believe that timing is a factor. On your question (3) our official advice is in the SARA-R4 system integration manual but we did an energy harvesting project a few years ago which used SARA-R4 and includes a schematic for the board we made which you may find useful. There's also the C030-R410M we designed for use with mbed-os which was never publicly released but I've attached the schematic in case it is useful to you. Finally, there was an internal project which made a small M.2 form-factor board containing SARA-R412M, NINA-W10 and a ZOE-M8 GNSS receiver, the schematic for which I've also attached. IMPORTANT NOTE: these schematics are offered in good faith for your information, neither I nor anyone in u-blox can support you with them since they are age-old projects that were never intended for external consumption in the first place! Just so's you know...

On the US network thing, the network registration timeout is set in that same config structure where you set the APN: you will see the line 240, /* Connection timeout in seconds */, so you can set it to what you wish. The network registration time-out is in no way connected with the AT time-out or the sockets time-out etc, it is entirely separate.

from ubxlib.

Thanks Rob, you're right, in sparkfun shield schematic also they connect the power-on and reset pins to the module, so I connected gpio 14 as power-on pin to Sparkfun shield D5 pin which toggles the power-On pin, I see the shield blue LED blinking as AT commands are sent to the board;

U_CELL: initialising with enable power pin not connected, PWR_ON pin 14 (0x0e) (and is toggled from 1 to 0) and VInt pin not connected.
U_CELL: initialising with enable power pin not connected, PWR_ON pin 14 (0x0e) (and is toggled from 1 to 0) and VInt pin not connected.
AT
U_CELL_PWR: powering on.
AT
AT
AT
AT
AT
AT
AT
AT
AT
AT
U_CELL_PWR: powering on.
AT
AT
AT
AT
AT
AT
AT
AT
AT
AT
Added network with handle -7.
Bringing up the network...
Network is not available!
1 Tests 1 Failures 0 Ignored

So I think we are one step closer to make it work!
Actually I saw the connected sign in dashboard.hologram.io where it shows last active! Which is a very promising sign!
I set APN to "hologram"
In terminal it says Network is not available!, but in hologram dashboard website it says connected! it looks like I should work more on rx tx on feather!

Does your code connect for a while and disconnects?
Can you develop some code to get IP address of a website, or connect to something like request library, to upload pictures?
Also, I guess in your Arduin instructions you mentioned how to transfer your IDF examples to arduino.ino codes, I will check that out!

Also I will strat designing our own Eagle sara-r4 breakout board with accessing more pins! Since this Sparkfun shield is designed mainly for Arduino Uno...

Btw, To set the mobile network operator, MNO, in Sparkfun library it is set is as follows;
MNO_ATT = 2
https://github.com/sparkfun/SparkFun_LTE_Shield_Arduino_Library/blob/master/src/SparkFun_LTE_Shield_Arduino_Library.h

In ublox, in some modules, they use +UMNOPROF, not sure it is supported by Sara-r4.

Regards,
MoZen

from ubxlib.

Thanks, Rob, yes Sparkfun lte shield has a level shifter, mentioned in the left part of page 1 of their schematic;
https://cdn.sparkfun.com/assets/3/9/d/5/f/lte_cat_m1_shield_schematic.pdf

So when I connect UART from ESP feather it goes to Sparkfun level shifter first, converting 3.3 V to 1.8V.
Yes, I bought those bidirectional level shifters too, but since Sparkfun had its own, and I can't directly access SaraR4 pins on Sparkfun shield, I refrained from using those, now I am actually designing in Eagle our own level shifter and ESP LTE shield using such level shifters you shared(I probably will have a prototype in two weeks)!

Meanwhile, if you got time, you can take a look at these popular examples of the Sparkfun shield and see if anything in them is useful being part of your codes;
https://github.com/sparkfun/SparkFun_LTE_Shield_Arduino_Library/tree/master/examples

Thanks for helping with the MNO code too.

Regards,
MoZen

from ubxlib.