DATA transmission/receiving using SCR Radio modules.

[ericgibbs]

hi C,
As I understand the datasheet, I believe the SX must in Standby when programming.

E

EDIT:
Are you following the TX procedure for OOK [On Off Keying] as per this image clip.

I would expect the TX RF output to be zero when not transmitting or when the transmitted data BIT is a '0' and full TX RF when the BIT is a '1'

https://en.wikipedia.org/wiki/On-off_keying

 

[camerart]

hi C,
1/ As I understand the datasheet, I believe the SX must in Standby when programming.

E

EDIT:
2/ Are you following the TX procedure for OOK [On Off Keying] as per this image clip.

3/ I would expect the TX RF output to be zero when not transmitting or when the transmitted data BIT is a '0' and full TX RF when the BIT is a '1'

https://en.wikipedia.org/wiki/On-off_keying

Hi Eric,
1/ If I don't get a change after a new setting, I add a STANDBY just before the setting, as I don't think STANDBY is always needed??
2/ I'm not sure! I keep trying different settings, as it is difficult to understand. From what you understand, how many connections between the PIC and SX do you think are needed (minimum).
If it is easier for you, I'm happy with DATA sheet reference, i,e, 4.2.1 =Transmitter Startup Time, and one I'm looking at in conjunction with TST is 5.3.1 =DIO Mapping, Continuous Mode. (This will save copy and past)
3/ Me to, but so far it looks opposite.

EDIT: What is Tbit?
c.

 

[ericgibbs]

EDIT: What is Tbit?

Hi,
I take it as a 'data Bit's time duration', it is dependent upon the data modulation rate of the RF signal

When you are testing for TX, are you actually writing data to the SX after receiving the TX Ready Interrupt.?

OR
just Enabling the TX Synth and Transmitter Block, which will NOT give a RF output.

E

 

[camerart]

Hi,
1/ I take it as a 'data Bit's time duration', it is dependent upon the data modulation rate of the RF signal

2/ When you are testing for TX, are you actually writing data to the SX after receiving the TX Ready Interrupt.?

OR
just Enabling the TX Synth and Transmitter Block, which will NOT give a RF output.

E

Hi,
1/ I presume, there needs a small delay, before Switching between TX and RX 'say' 1ms for now??
2/ No, I've just been TX--RX, which as you say doesn't work.
3/ Regarding RegDioMapping Do you think I need all of the PINs connected or will it work with two e,g, TX= DIO2 set to DATA and DIO5 set to TXREADY and RX= DIO2 set toDATA and DIO5 set to RXREADY? OR as you mentioned in 2/ Do I need to connect a PIN to receive the TX and RX ready BIT?

C.

 

[ericgibbs]

3/ Regarding RegDioMapping Do you think I need all of the PINs connected or will it work with two e,g, TX= DIO2 set to DATA and DIO5 set to TXREADY and RX= DIO2 set toDATA and DIO5 set to RXREADY? OR as you mentioned in 2/ Do I need to connect a PIN to receive the TX and RX ready BIT?

hi C,
There maybe on board pull ups on the DIO pins, so it may require the unused DIO's to be pulled Low.?????
When the SX is powered up, measure the voltage on the unused DIO pins as a check.

What does the SX d/s say regarding unused pins.?
E

Clip from d/s ref DIO

 

[camerart]

hi C,
There maybe on board pull ups on the DIO pins, so it may require the unused DIO's to be pulled Low.?????
1/ When the SX is powered up, measure the voltage on the unused DIO pins as a check.

2/ What does the SX d/s say regarding unused pins.?
E

Clip from d/s ref DIO

Hi E,
1/ Single figure mV
2/ Nothing.

P.S. As mentioned before: I have the DATA sheet, and am happy for you to post references e,g, 5.3.1 = Table 20. It will save you posting Gifs.

C.

 

[camerart]

Hi,
Setting RegDioMapping 1 and 2
If I understand correctly for the minimum of PINS, there needs to be 1 PIN reading the TXREADY BIT (Which could be the TBIT??) and needs a little time before reading it, 1PIN for MODEREADY and 1 PIN for DATA.

So using the minimum PINS, 1/TXREADY--2/ MODEREADY and--3/ DATA.

If DIO3 is chosen for TXREADY. DIO5 for MODEREADY and DIO2 for DATA.

RegDioMapping1 for PINS 0-3 and RegDioMapping2 for PINS 4-5 plus CLKOUT frequency.

=RegDioMapping1 %1111xxxx sets PINs DIO3 and 2
=RegDioMapping2 %xx110111 sets PIN DIO5 and CLKOUT OFF.
C.

 

[ericgibbs]

hi C,
Your description looks OK to me.
We are assuming that DIOX is represented by Bit 7 and 6 of the Byte being loaded into Registers 0x25 and 0x26.
E
BTW:
I would suggest that you discover what will be maximum range of the Transceivers when using OOK rather than Lora.
From the brief notes I have read it suggests that the Lora mode is required for ranges up to 1 mile.
The RF power output is only 100mWatt.???

 

[camerart]

Double posting

 

[camerart]

Hi,
#57 Shows a couple of errors! I misread the DATA sheet BITs e,g, TXMODE should be %00001100, not %00000011. I think you thought when I added BIT7 =1 that it was for the WRITE bit, but it was to switch off the sequencer.
With sequencer off TXMODE should be %10001100 0x8c.

I've tried this setting, but still no transmission

Now I've got to climb over this dead end

C.

 

[camerart]

Hi,
I've been none stop trying to get the SX1231 CHIP/MODULES working, but after checking CHIP PINS to BOARD PINS, couldn't find where PIN19 RXTX connects to. This is used to switch between RX and TX. So I've almost given up on these SX1231 CHIPS. This may be why in the beginning I got it to transmit, and now it doesn't.

I've switched to SX1278. Beware buying incorrect CHIPs, I've just spent weeks trying to get incorrect chips to work!!
C.

 

[ericgibbs]

hi C,
Who the supplier and type number of the assembled PCB.?
E

 

[camerart]

hi C,
Who the supplier and type number of the assembled PCB.?
E

Hi Eric,
I can't vouch for them, but they look like the most likely, and economic I could find: https://www.ebay.co.uk/itm/191279482237?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
C.

 

[camerart]

Hi,
Here's what I've got so far. I've put the program in #1 18F2420 8MHz-INT SX1278 OOK TX SLEEP 130117 1200
At about a metre it shows a signal on SDR# see image. And when the aerial is connected to an oscilloscope it shows 0.1V spike, see image.
There is something happening, but I could be only getting the signals from the oscillator.
any ideas, anyone?
C.

 

[camerart]

Hi,
I've updated the 18F2420 8MHz-INT SX1278 OOK TX 190117 1000 program in #1 to a simpler version.
Sadly same poor results as shown in #74
C.

 

[camerart]

Hi,
I have at last got an SX1278 to transmit With the supplied coiled spring aerial, 100mtr range after a quick test. I've updated Post #1

All connections between the 18F2420 PIC and the SX1278 have a series resistor on them, as a make do for voltage matching.

I've made two circuits, but so far, I can only get one of the SX chips to transmit.

If anyone is testing these chip-modules, I would appreciate any feedback please.

C.

 

[camerart]

Hi,
I've now got both circuits to work. After inputs from ETO members on other threads, I took their advice and shortened the connecting leads, especially SCK and MISO for the TX test.
Similar circuits, where they are surface mount and have very short connections, and in one instance the radio and the controlling chip are directly opposite each other on the circuit board.
I will next make test circuits using Surface mount components, if I can solder them successfully
C.

 

[camerart]

Hi,
I tried a test with my two working veroboards, program one as TX and the other as RX. A strange thing happened when programming the RX, I couldn't program any byte with *****101. The correct byte for RX is 0x2d, but it is 'corrected' to 0x2c. I tried every byte ending 101, from 0x04-0x5d, all were 'corrected' to *****100.
Any ides?
C.

 

[ericgibbs]

hi C,
One cause maybe that earlier in your code you have set a mode that is not permitting a Write 0x2d instruction as being valid.
How have you decided that RX mode is 0x2d.?
E.
Please post a link to the SX datasheet so that I can relook.

 

[camerart]

hi C,
One cause maybe that earlier in your code you have set a mode that is not permitting a Write 0x2d instruction as being valid.
How have you decided that RX mode is 0x2d.?
Please post a link to the SX datasheet so that I can relook.

Hi Eric,
I had a similar thought that I had broken a rule, I'll re-look.
I've updated the RX byte selection, in post #78
I've posted the RX program and SXPDF link in post #1.
C.