ESP8266 Community Forum

Posted: **Wed Mar 11, 2015 1:13 pm**

Hi, I'm looking to send hex commands to a fingerprint sensor connected to a cp2101 board.
For that, i'm trying the following code (The sensor works only in 115200):

Code: Select all

    uart.setup( 0,115200,8,0,1,0 )
    srv=net.createServer(net.TCP) 
    srv:listen(80,function(conn) 
       conn:on("receive",function(conn,payload) 
          uart.write( 0, "0x55AA24010200010000000000000000000000000000002701")
          conn:send("<h1> Turning on LED.</h1>")
          end) 
       conn:on("sent",function(conn) conn:close() end)
       end)

Is it ok to send an hex command in that way? What could be wrong?

Posted: **Wed Mar 11, 2015 6:49 pm**

Hi

uart.write can only send one byte at a time
try uart.write( 0, 0x55,0xAA,0x24,......).

Gerry

Posted: **Thu Mar 12, 2015 9:42 am**

Hi Gerry, thank you for your reply, I've tried and it worked perfectly.

It is just a little tedious to write every byte of 15 bytes-length command (I have to pass like 10 of this commands), but is the only way..

Thanks again!

Posted: **Thu Mar 12, 2015 10:29 am**

Hi
Would attached be any use

Code: Select all

msg = "55AA24010200010000000000000000000000000000002701"

for i = 1,string.len(msg),2 do
byte =("0x"..string.sub(msg,0+i,1+i)) 
uart.write(0,tonumber(byte))
end

ESP8266 Community Forum

Hex commands through UART

Hex commands through UART

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Re: Hex commands through UART

Re: Hex commands through UART