PICAXE-28X2/AXE401 Serial Coms withe DRA818 U/V


New member
Good day

Im strugeling to comunicate withe a DRA818V and U withe a PICAXE-PICAXE-28X2 Micro controler withe a AXE401 project board.

The project is to make a croseband radio repeter withe 2 DORJI DRA818 radios. Hrer is the steps i follow:

1) I configer the coms pord withe the command "hsersetup B9600_8, %0010"
2) next switch withe relays the C6 and C7 outpots to the selected radio modul that i want to configer.
3) Then I make the radio sleep mode pin, "Pin 6 PD "High to wake it up from the cpu before I start sending the AT comand from the 28X2
4) Then i send the comstest message to the radio (AT+DMOCONNECT<CR><LF>) withe this command: " hserout 0,("AT+DMOCONNECT",CR,LF) "
5)Then i read back the Respons from te DRA818 and get a "+DMOERROR" insted of " +DMOCONNECT:0 "

The reply +DMOERROR mesage is not described in the DORJI DRA818V/U Datasheet and i have asked them for more information in ther website we will see if i get responce from them.

In the mean time do anyone have segestions on what i can do to fix this problem?



Senior Member
In the mean time do anyone have suggestions on what I can do to fix this problem?
In the Arduino world, all the examples seem to use this library. I can see that it too sends "AT+DMOCONNECT\r\n", but it seems to accept any response as meaning "success". (My C++ isn't the best :().

Perhaps there is some intrinsic bug with the device, that everyone just ignores?...

There's a discussion HERE, where someone else encounters this. They seem to have resolved the issue, but it's not entirely clear how :unsure:

I would suggest taking the Picaxe out of the equation to start with; use a terminal emulator like Realterm to test communications with it first. (Realterm is quite flexible; it can display data in hex and add CR,LF automatically etc. It can also send predetermined strings).
Last edited:


New member
Thanks for all the feadback I realy aprisiate it. I was looking at a lot of forum enterys yesterday and unfortunatly i can not find it agen. in a progeram that was written by Bill Roth / Goeytex for a DORJI DRF7020D20 he setup the com port as follow hsersetup b9600_16,%00001 '(Invert = True, Background receive on) This trigerd me lastnight to set myn to hsersetup B9600_8, %00001 And wala it work. So Inglewoodpete you were write. This brings me to the confusing descriotion of the "hsersetup" command in the manial.

HSERSETUP baud_setup, mode

Baud_setup - is a variable/constant which specifies the baud rate:

B300_Xwhere X =
B600_X4 for 4MHz
B1200_X8 for 8MHZ
B2400_X16 for 16MHz
B4800_X20 for 20MHZ
B9600_X32 for 32MHz
B19200_X40 for 40MHz
B31250_X64 for 64MHz
Mode - is a variable/constant whose bits specify special functions (not all features are supported on all chips) :

bit0 - background receive serial data to the scratchpad (not M2 parts)
bit1 - invert serial output data (0 = ‘T’, 1 = “N”)
bit 2 - invert serial input data (0 = “T”, 1 = “N”)
bit 3 - disable hserout (1 = hserout pin normal i/o)
bit 4 - disable hserin (1 = hserin pin normal i/o)

In the Mode %00001 where is Bit 0 then do this mean that the PICAXE-28X2 stop background receive serial data when you invert serial?
In my case it do not look like it becouse i captur the feadback from the module
this was how i understoot the %00000 = % (bit4) (bit3) (bit2) (bit1) (bit0) if im corect the description im the manial is not corect and verry confusing.

The sade thing is this problem kepet me buzy for a month to solve :)
I still have to see if i can chanch the second radios frequincy unfortunatly my time was Hiject by Loassheding in Southe Africa lastnight before i culd try it on the second radio module so i do not know if it was just pure luck or if it is the real selution to the problem. I will try tonight and let you know what happond.
Last edited: