Hello. I am doing my very first steps with BC660K-GL modules. Because I am working under time pressure, I cannot do endless trial & error.
I designed a first PCB for it, but because I cannot find answers to some questions in documents I found, I want to ask here. I used a M35 module based modems years ago. I got that ones working well in shortest time, but I never used this particular NB module before. It also seems to be a bit different in operation.
My questions:
Powering up/down
M35 had an input “Power Button”, allowing me to to turn it on|off by applying a pulse of some duration. So in worst case, I could turn it off|on to get it back into a known condition. I could not find this functionality in any document of BC660K-GL. I made RESET and PSM_EINT accessible from MCU by a BC817 transistor, I hope this is sufficient.
How can I enforce a complete cold-boot of BC660K-GL from my microcontroller without doing a physical power off|on ?
Controlling Power mode.
Is there a way to normally have the module running without any powersaving, but to immediately send it to powersave by an AT command? Or can I configure BC660K-GL to switch to a mode where I am able to read signal quality and network connecttion|registration without having to wake it up completely?
I would like to show an icon with signal strength and ifg it is registered or not (like on smart phone), but resources are very limited on MCU side…
Program Flow chart
Is a program flow chart available, showing a usual startup initialization sequence, opening of a TCP/IP, transmission of data, closing connection, return into low power mode?
Documentation is hundreds of pages, showing countless commands, but it is difficult to pick out the correct setup sequence from there. It would be very time saving to have a typical sequence for this and that at hands.
It would be very kind if you could provide me answers to above questions.
1.BC660K automatically starts after power-on, without powerkey pin, you need to control power supply or power off through MCU; If the BC660K does not need to work after power on, you can run AT+CFUN=0,AT+QSCLK=1 to enter the deepsleep state.
For questions 2 and 3, you need to wait a few days. Now I am sorting out the documents in this respect, and I will send them to you for reference when they are completed
My current PCB uses an LD1117AS33TR low drop linear regulator (5V → 3.3V). The regulator has big copper areas around (as heat sink) and many vias very closely around its big pin for heat conducting to bottom side of PCB. Is this - combined with 200uF Tantalum Capacitor and all other capacitors listed in Hardware Application guide sufficient for reliable operation?
As you see hereby, this BC660K-GL will be permanently powered and therefore boot up immediately. This is fine for me. Knowing the command sequence you provided, I will set it into deep sleep then.
Waking up from deep sleep happens by pulling PMU_EINT low (by open collector transistor) for some [ms] and then let this pin float again?
In case the BC660K-GL somehow gets into a “dead state”, responding to no AT commands (i.e. caused by a brownout or whatever)… Can I pull /RESET low to get it back operational without any power cycle?
I have another question not answered in any documentation:
Does the main UART do auto baudrate detecting by default, or is it fixed to 115 kBit by default? I don’t want to use such high baud rate, also not at startup, I would prefer to have 19200bps or 38400bps continuously. I slightly remember that the M35 modem did auto-bauding.
The reason for my question: I would like to send repeatedly “AT” command until the BC660K-GL responds with “OK”. This way I will give it all time it needs for wakeup.
1.If the BC660K enters the dead state, I suggest that you control it through the RESET pin, or the MCU monitors whether the RESET responds normally. If there is no response, it is recommended that you directly power off
2.The default baud rate of the BC660K is 115200, which you can configure through the command AT+IPR
3.You can wake up by AT or PSM_EINT