ESP8266 WiFi Module with multi-session HTTP API (pure MMBasic)
This is a complete ESP8266 module that will connect to the WiFi of your choice and then accept connection inbound. No CFunctions or anything, purely handling a serial port and chopping up whatever comes through. It works really well and is fast. It handles multiple inbound connections - up to five at a time. It looks like a big deal but a lot of it is simply functions to make string handling easier (at the bottom).
This might be for a MicroMite based web server or to allow you to set the MicroMite doing things. Here I don't write back HTML (API doesn't require it) but you could just as easily, you could ask for status on bits, analogue inputs. You could send Instructions for quite complex activities, your imagination is the limit.
This is an extract (with changes) from my SMS Gateway. I connect in with a web page and issue commands via this collection to send text message from my website. This bit works perfect, all the time… (the M590 GSM module is more temperamental and I have some work to do before I can publish that bit).
This is enough to get you going, you have to pick the bones apart of the main loop and understand what is happening but it is mainly just detecting the inbound connection and then using string slicing to pick apart the HTTP request to see what is being asked for.
Here's a load of links I used when I was getting this working. Research loads!
https://alselectro.wordpress.com/2015/05/13/wifi_module_esp8266_2_tcp_client_server_mode/
https://www.sparkfun.com/products/13678
http://www.instructables.com/id/Using_the_ESP8266_module/
http://www.instructables.com/id/Using_the_ESP8266_module/step3/Configuring_the_8266_Module/
http://www.instructables.com/id/How_to_Build_a_ESP8266_Web_Server/step7/Results/
https://github.com/esp8266/esp8266_wiki/wiki
http://www.esp8266.com/
http://dominicm.com/esp8266_send_receive_data/
https://www.youtube.com/watch?v=aqjx_85_hwg
https://cdn.sparkfun.com/datasheets/Wireless/WiFi/Command%20Doc.pdf
http://41j.com/blog/2015/01/esp8266_client_mode_connect_remote_host_simple_example/
Enjoy
'
'ESP8266 Module. Andrew Henderson. October 2016
'
'Preamble
OPTION BASE 0
CONST LAN=2
'S/W Init
DIM STRING A$,B$,D$
DIM STRING LNBuf$
DIM STRING LANRxLN$,LANTxLN$,TChr$ LENGTH 1
DIM INTEGER C,Z,TOFg,Chan,Conn(4),PingTMR,PingCtr,RL1TMR LANf
DIM FLOAT x
'Starting WLAN Interface
Open "COM2:9600,1024" As #LAN
ESP8266Reset
Main:
' don't do this every time through the loop, set a timer for no more than 60second intervals {
'Test Internet connectivity - you'll have to handle what to do if this is broken, there's nothing here for it.
A$=ESP8266Exec$("AT+PING="+PA,4000,0) ' PA=Ping address. try to be nice here and set this to a DNS server from your ISP e.g. 100,200,111,222 or www.bbc.co.uk or something that won't mind you pinging them
IF A$="OK" THEN
'good
'...
ELSE
'internet down
'...
END IF
}
'Web API parsing
LANRxLN$=GetIO$(LAN,1)
IF LANRxLN$="" OR LANRxLN$="T/O" THEN GOTO Main ' nothing waiting on the input
IF MID$(LANRxLN$,2,8)=",CONNECT" THEN ' ESP8266 provides the connect as an indication of HTTP input
Chan=VAL(LANRxLN$)
IF Chan>=0 AND Chan<=4 THEN
Conn(Chan)=1
PRINT "Inbound connect channel "+STR$(Chan)
'Inbound connect channel on channel 0 - 5
GOTO IPEXIT
END IF
END IF
IF MID$(LANRxLN$,2,7)=",CLOSED" THEN ' ESP8266 provides the closed as an indication of HTTP channel closing
' either coz it was explicit or it timed out
Chan=VAL(LANRxLN$)
IF Chan>=0 AND Chan<=4 THEN
IF Conn(Chan)=0 THEN A$=" Abnormally " ELSE A$=""
PRINT "Closed channel "+STR$(Chan) + A$
Conn(Chan)=0
GOTO IPEXIT
END IF
END IF
IF LEFT$(LANRxLN$,5)="+IPD," THEN
Chan=VAL(MID$(LANRxLN$,6,1))
IF Chan>4 THEN GOTO IPDerrEXIT
IF Conn(Chan)<>1 THEN GOTO IPDerrEXIT 'channel not open
z=INSTR(LANRxLN$,":GET /<my page, e.g. index.htm>") ' +IPD,0,nnn:GET /index.htm HTTP/1.1
do:a$=GetIO$(LAN,2):loop until a$="Connection: Keep-Alive" ' empty the rest of the envelope, this string is the last part of an HTTP connection header
IF z=>8 AND Z<=11 THEN ' checking for the position of the arguments in the string - your mileage will vary... simple sanity check
b$=MID$(LANRxLN$,z+13)
z=INSTR(b$," HTTP/")
IF z<21 THEN GOTO IPDerrEXIT '... and again
b$=LEFT$(b$,z-1) ' remove the HTTP bit
b$=Replace$(b$,"+"," ")' + to spaces
args=Split(b$,"?") ' split the request arguments out
IF args <3 THEN GOTO IPDerrEXIT ' your arguments might vary - I have two, the header + two arguments = 3 strings from the spilt
FOR n=2 TO args 'args=1 is a dummy
SELECT CASE LEFT$(ucase$(SP$(n)),4) ' check for the name of the argument here and assign the value to a variable
CASE "VAR1="
var1$=LTrim$(RTrim$(MID$(sp$(n),5)))
CASE "VAR2="
var2$=LTrim$(RTrim$(MID$(sp$(n),5)))
END SELECT
NEXT
IF var1$="" OR var2$="" THEN GOTO IPDerrEXIT ' don't allow empty values - your mileage may vary
ERASE SP$
Msg$=URLDecode$(Msg$)
' other api calls go here, I only have one in this application
END IF
GOTO IPDerrEXIT 'default action IF we don't find an API call
END IF
GOTO IPEXIT
IPDerrEXIT:
B$="ERROR: Malformed request {"+LANRxLN$+"}"
IPOKEXIT:
PRINT #LAN,"AT+CIPSENDEX="+STR$(Chan)+",255" ' send our response back to the requestor
PAUSE 100
PRINT#LAN,B$+"\0"
PAUSE 100
PRINT#LAN,"AT+CIPCLOSE="+STR$(Chan) ' then close the channel nicely
Conn(Chan)=0
IPEXIT:
GOTO Main
END
'------------------ ESP8266 WiFi Modem SUBsys -------------
SUB ESP8266Reset
LOCAL STRING A$
LOCAL INTEGER N
PULSE LANRST,10 ' whatever pin you have connected to the reset of the ESP8266
PAUSE 400
LANExec "ATE0",2,0
LANExec "AT+CWAUTOCONN=0",2,0 ' turn off autoconnect while we initialise
LANExec "AT+CWMODE=1",2,0
LANExec "AT+CWQAP",4,0 ' disconnect any existing WiFi connections
LANExec "AT+RFVDD",2,0
LANExec "AT+CWJAP="+AP+","+PW,10,1 ' AP= name of the network you want to join e.g. your WIFI SSID - and PW= it's password
LANExec "AT+CIPSTA="+IP+","+GW+","+MS,2,0 ' the IP and Gateway address for static IP addresses, rem this line for a static IP
LANExec "AT+CIFSR",2,0
LANExec "AT+CWAUTOCONN=1",2,0 ' turn autoconnect back on so if the WiFi drops, the ESP8266 will self negotiate to get it back
LANExec "AT+CIPMUX=1",2,0
LANExec "AT+CIPSERVER=1,19090",2,0 ' turn on the server with the port you want your API to listen on, normally HTTP is 80 or sometimes 8080, here I listen on 19090... you can use anything from 1 - 65536 but as a guideline; avoid anything below 1000 if you are not using 80
LANTxLN$="":LANRxLN$="" ' buffers for receive and transmit
FOR N=0 TO 4:Conn(N)=0:NEXT ' clear the channel connection flags
END SUB
SUB LANExec(CM$,T,Suppress) 'temp - will go when we have better handling of the startup
LOCAL STRING A$
A$=ESP8266Exec$(CM$,T,Suppress)
IF Suppress<2 THEN CLog A$,0
END SUB
FUNCTION ESP8266Exec$(Com$,TimeOut,Obf)
LOCAL STRING A$ LENGTH 1,LN$
LOCAL INTEGER C
PRINT #LAN,Com$
DO
LN$=GetIO$(LAN,TimeOut)
IF LN$="T/O" THEN ESP8266Exec$="T/O":EXIT DO
IF LN$<>"" THEN
IF Obf<2 THEN CLog "["+LN$+"]",0
IF LN$="OK" OR LN$=">" OR LN$="SEND OK" THEN ESP8266Exec$=LN$:EXIT DO
IF INSTR(LN$,"ERROR") THEN ESP8266Exec$="ERROR ["+LNBuf$+"]":EXIT DO
END IF
LOOP
END FUNCTION
'----------------------------------------------------
FUNCTION GetIO$(io,TimeOut)
LOCAL STRING a$,b$
LOCAL INTEGER c
StartTOTimer TimeOut
DO
IF TOFg=1 THEN GetIO$="T/O":EXIT DO
IF LOC(#io)<>0 THEN
A$=INPUT$(1,#io):C=ASC(A$)
SELECT CASE C
CASE 13
GetIO$=b$:EXIT DO
CASE 0 TO 31
CASE ELSE
IF LEN(b$)+LEN(a$)<255 THEN b$=b$+a$ ELSE b$=a$
END SELECT
END IF
LOOP
ClearTOTimer
END FUNCTION
SUB FlushIO(stream)
LOCAL STRING A$
DO WHILE LOC(#stream)<>0
PAUSE 50:A$=INPUT$(LOC(#stream),#stream):PAUSE 50
LOOP
END SUB
FUNCTION Replace$(a$,b$,c$)
LOCAL INTEGER z
LOCAL STRING x$,y$
z=1
DO
z=INSTR(z,a$,b$)
IF z=0 THEN EXIT DO
x$=LEFT$(a$,z-1):y$=MID$(a$,z+LEN(b$)):a$=x$+c$+y$:z=LEN(x$)+LEN(c$)
LOOP
Replace$=a$
END FUNCTION
FUNCTION URLDecode$(a$)
LOCAL INTEGER z
LOCAL STRING b$,c$
z=1
DO
z=INSTR(z,a$,"%")
IF z=0 OR z=LEN(a$) THEN EXIT DO
b$=MID$(a$,z,3):c$=CHR$(VAL("&h"+MID$(b$,2))):a$=Replace$(a$,b$,c$)
LOOP
URLDecode$=a$
END FUNCTION
FUNCTION LTrim$(a$)
LOCAL INTEGER m
FOR m=1 TO LEN(a$)
IF not(MID$(a$,m,1)=" " OR MID$(a$,m,1)=CHR$(9)) THEN LTrim$=MID$(a$,m):EXIT FUNCTION
NEXT
LTrim$=""
END FUNCTION
FUNCTION RTrim$(a$)
LOCAL INTEGER n
FOR n=LEN(a$) TO 1 STEP -1
IF not(MID$(a$,n,1)=" " OR MID$(a$,n,1)=CHR$(9)) THEN RTrim$=LEFT$(a$,n):EXIT FUNCTION
NEXT
RTrim$=""
END FUNCTION
FUNCTION Split(a$,b$)
LOCAL INTEGER z,n,m
ON ERROR SKIP
ERASE SP$
z=1:n=0
DO
z=INSTR(z,a$,b$)
IF z=0 THEN
IF n=0 THEN
DIM SP$(1):SP$(1)=a$:Split=1:EXIT FUNCTION
ELSE
EXIT DO
END IF
ELSE
n=n+1:z=z+LEN(b$)
END IF
LOOP
m=n+1:n=1
DIM SP$(m)
DO
z=INSTR(1,a$,b$)
IF z=0 THEN
SP$(m)=a$:EXIT DO
ELSE
SP$(n)=LEFT$(a$,z-1):a$=MID$(a$,z+LEN(b$)):n=n+1
END IF
LOOP
Split=m
END FUNCTION