Refoss Smart Wi-Fi Garage Door Opener

I bought an "add-on" device that will enable my garage door opener accessible via WiFi, as well as other automated processes as part of my home automation project last year.  I bought it on Amazon: https://www.amazon.com/Refoss-Garage-Control-Compatible-Assistant/dp/B07PM59X4J/ref=cm_cr_arp_d_product_top?ie=UTF8&th=1

It had been working perfectly since I installed it last year, but since the last few days ago it has stopped.  I thought it must be something with the networking, so I followed the procedure instructed on the manual to configure it as a new device added to the eHomeLife on my iPhone, but with no luck.  The manual says, if the WiFi LED blinks rapidly, the device has been correctly set to access our home network.  But, I have not been able to connect my app to the device.

Curious to see what was going on, I logged on to my AP router and could see the device had been assigned a valid IP address (192.168.1.55) and I could even ping it.  That's all. I then did nmap to the device to see what ports were open.  I could only see the following:

nmap -O -sO 192.168.1.55
WARNING: Disabling OS Scan (-O) as it is incompatible with the IPProto Scan (-sO)
Starting Nmap 7.80 ( https://nmap.org ) at 2020-07-05 21:44 Pacific Daylight Time
Nmap scan report for 192.168.1.55
Host is up (0.021s latency).
Not shown: 252 closed protocols
PROTOCOL STATE         SERVICE
1        open          icmp
6        open          tcp
17       open          udp
41       open|filtered ipv6
MAC Address: 48:E1:E9:51:07:50 (Chengdu Meross Technology)

Actually, if I press the WiFi button for more than 5 seconds to make it goes to configuration mode and then use the SSID of the device (it becomes an "AP" device temporarily), then open a browser to access it (at IP address 10.10.10.1, because my phone's IP was assigned 10.10.10.2), I could see basic web interface to set WIFI as well as to upgrade firmware.

Googling for "Meross" or "Refoss" firmware couldn't give anything.  The company's website also doesn't give any link or information about any firmware upgrade.  Also, What's the difference between "Meross" and "Refoss"? Is Refoss is a knock-off of Meross?  Both are Chinese companies.

Honestly, I am now tempted to develop a similar by myself, probably using ESP32 (as using Raspberry-Pi for such thing is too much for such thing, not to consider more power-hungry).

Create Delay using Number of Cycles in PIC MCU

Most of the delay code available on the Internet for PIC is based on real time delay.  The problem with this approach is that it's hardcoded for certain clock frequency only.  When we use the code for different frequency clock, we have to change the code, sometimes drastically.

Another approach is just to make a routine to waste number of instruction cycles, regardless of the clock frequency.  The caller then later calculate how many cycles it needs to waste in order to get the wanted delay.  It's more maintainable this way than the former.  All PIC MCUs have each instruction executed in 4 clock frequency, or F_cy = F_clock/4, hence T_cy = 1/F_cy = 4/F_clock.

Here is the example of the code for PIC16F877A to waste 10 T_cy cycles.  If F_clock is 16 MHz, F_Cy = 4MHz and T_Cy = 0.25 uSec.  So 10*T_cy = 2.5 uSec delay.
I don't see any reason it won't be compiled and working on other pic16-based MCUs.  I compiled the code with gpasm and header file from sdcc.
 


    title "Delay 10 Tcy"

    include <p16f_common.inc>

    list n=0

    radix    dec
    global    _delay10tcy
    extern   _d1
 
; -----------------------------------------------------------------------
; Variables declaration
;DLY_VAR UDATA_SHR  0x190
;WREG         res 1
WREG        equ     _d1



code_delay10tcy code

_delay10tcy:
    ; polynomial for 10tcy delay is f(x) = 10 + 10 * (x-1)
    ; caller takes 2 TCy, return takes 2 Tcy, so we need 6 more Tcy here
      banksel   WREG            ; 2 Tcy
      decf      WREG,f          ; (x-1), 1 TCy.  TCy so far = 4 + 2 + 1 = 7

      movfw     WREG            ; 1, TCy so far = 8
      bz        @delay10_end    ; 2 Tcy if x=0, otherwise 1, TCy so far = 9 (if x>0)
      nop                       ; 1 TCy, TCy so far = 10

@delay10_loop:                  ; (x-1) * 10
      goto       $+1            ; 2 TCy, TCy so far = 2
      goto       $+1            ; 2 TCy, TCy so far = 4
      goto       $+1            ; 2 TCy, TCy so far = 6

      nop                       ; TCy so far 7
      decfsz    WREG, f         ; TCy so far 8 (if x>0), else 9
      goto       @delay10_loop  ; TCy so far 10
      nop                     

@delay10_end:

      return                    ; 2

      end


Save the code to a file name delay10tcy.S.

To compile it on Linux:

gpasm -c -M -m --mpasm-compatible -e ON -DSDCC -Dpic16f877a -p16f877a -I/usr/local/share/sdcc/include/pic14  delay10tcy.S

The variable "_d1" above has been defined elsewhere as 8-bit user data (so it's shareable among other delayxtcl routines), but if we want to make it local just declare is such as:

DELAY_VAR  udata_shr 0x190
d1  res 1

and remove underscore in all references to d1.