Sir, I have send sms in PDU formate through AT commands. AT+CMGS=18 0011000C912933634241140000AA04D370DA0C
Message send successfuly.But when i am trying to send message with UDH & UDHL i am using the Following At Command but show me Error ..... AT+CMGS=24 0011000C912933634241140000AA05000303020104D370DA0C What is the wrong in my code please help me.
Is it 7 bit encoded? I'm trying to solve this problem myself, and the problem itself is that your UDH requires the message part (04D370DA0C) to be padded (at least in my case).
The text below is from https://en.wikipedia.org/wiki/Concatenated_SMS#PDU_Mode_SMS
the UDH is a total of (number of octets x bit size of octets) 6 x 8 = 48 bits long. Therefore, a single bit of padding has to be prepended to the message. The UDH is therefore (bits for UDH / bits per septet) = (48 + 1)/7 = 7 septets in length.
With a message of "Hello world", the [message] is encoded as
90 65 36 FB 0D BA BF E5 6C 32
as you need to prepend the least significant bits of the next 7bit
character whereas without padding, the [message] would be
C8 32 9B FD 06 DD DF 72 36 19
and the UDL is 7 (header septets) + 11 (message septets) = 18 septets.
