Problema conversione array

mi esce sempre lo stesso errore e si sconnette

char s[4];
strcpy(s,ptr2);
mySerial.write(s);

New Client connected
GET /?10&10 HTTP/1.1
main
path /main
req: GET /?10&10 HTTP/1.1
len: 20
10
10 HTTP/1.1

Fatal exception 28(LoadProhibitedCause):
epc1=0x4000bf0e, epc2=0x00000000, epc3=0x00000000, excvaddr=0x00000000, depc=0x00000000

Exception (28):
epc1=0x4000bf0e epc2=0x00000000 epc3=0x00000000 excvaddr=0x00000000 depc=0x00000000

ctx: cont
sp: 3ffef800 end: 3ffefb20 offset: 01a0

stack>>>
3ffef9a0: 00000001 3ffeea34 3ffefad0 4020243a
3ffef9b0: 20544547 3031002f 20303100 50545448
3ffef9c0: 312e312f 00000000 00000010 ffffffff
3ffef9d0: 4010721c 037b47fb 00000000 3ffee8f8
3ffef9e0: 000003e8 00000000 00000000 fffffffe
3ffef9f0: 00000120 3fffc6fc 00000001 3ffee8a0
3ffefa00: 00010401 3fffdad0 3ffeeaf0 00000030
3ffefa10: 40204a04 00000030 00000010 ffffffff
3ffefa20: 40204a04 3ffeeb00 402049f8 00000000
3ffefa30: 00000000 00000000 00000000 fffffffe
3ffefa40: ffffffff 3fffc6fc 00000001 3ffeeb00
3ffefa50: 00000000 3fffdad0 3ffeeaf0 00000030
3ffefa60: 00000000 3fffdad0 3ffeeaf0 00000030
3ffefa70: 4010590e 00000001 00000000 00000000
3ffefa80: 00000000 3ffefae8 3ffee7f4 3fff03d4
3ffefa90: 0000000f 00000000 3fff0ecc 0000001f
3ffefaa0: 00000014 00000000 000003e8 4010068c
3ffefab0: 00000000 3fff0efc 3ffee96c 3ffeeaf0
3ffefac0: 3fffdad0 00000000 3ffeeae8 402024c1
3ffefad0: 3ffe86c0 00000000 000003e8 0000e42d
3ffefae0: 3ffefae8 3fff0efc 3ffe86c0 00000000
3ffefaf0: 000003e8 00000000 00000000 3fff0efc
3ffefb00: 3fffdad0 00000000 3ffeeae8 40204a18
3ffefb10: feefeffe feefeffe 3ffeeb00 40100718
<<<stack<<<

ets Jan 8 2013,rst cause:2, boot mode:(1,7)