External LNB power with the MiniTiouner question please?
Re: External LNB power with the MiniTiouner question please?
Thanks mike, i will check and if needed replace the 74ls10 after ive had some dinner and see where we go from there.
Nigel
Nigel
Re: External LNB power with the MiniTiouner question please?
It seems to be picking up a duplicate packet start byte (0x47), so definitely check the signals on the 74HC10 and see that the output gets to the FT2232H.
A 188 byte packet should start every 4 lines (green squares) but actually starts every 189 bytes (red squares) due to the extra 0x47.
Brian
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A 188 byte packet should start every 4 lines (green squares) but actually starts every 189 bytes (red squares) due to the extra 0x47.
Brian
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Re: External LNB power with the MiniTiouner question please?
Thanks Brian - I was just trying to look up the packet structure to understand it.
Comparing with what I hope is a valid TS extract: So why ? I think perhaps the device is glitching - this could be the NIM or perhaps the 74HC10. A photo of it might help.
Looking at the file it's not just that one byte being duplicated, it's other bytes duplicated or perhaps missing as well. Noise on the byte clock signal? Faulty FTDI module? Glitchy TSSync?
Mike
Comparing with what I hope is a valid TS extract: So why ? I think perhaps the device is glitching - this could be the NIM or perhaps the 74HC10. A photo of it might help.
Looking at the file it's not just that one byte being duplicated, it's other bytes duplicated or perhaps missing as well. Noise on the byte clock signal? Faulty FTDI module? Glitchy TSSync?
Mike
Re: External LNB power with the MiniTiouner question please?
It seems to have good and bad patches. Difficult to say whether it's a component fault or some data dependent shorting.
Here are some scope traces:
The photo below has the lower trace on 74HC10-10, which is the VALID signal from the NIM, which goes high when a packet is being output. The upper trace is on 74HC10-8, which is the strobe output to the FT2232H, which clocks in each byte.
. .
The photo below is an expanded version, showing the phase of the strobe signal relative to the VALID signal.
. .
Also check pin2-17 on the FT2232H, which is the SYNC signal from the NIM. It should be a pulse one clock wide, going high in phase with the VALID signal going high.
Brian
Here are some scope traces:
The photo below has the lower trace on 74HC10-10, which is the VALID signal from the NIM, which goes high when a packet is being output. The upper trace is on 74HC10-8, which is the strobe output to the FT2232H, which clocks in each byte.
. .
The photo below is an expanded version, showing the phase of the strobe signal relative to the VALID signal.
. .
Also check pin2-17 on the FT2232H, which is the SYNC signal from the NIM. It should be a pulse one clock wide, going high in phase with the VALID signal going high.
Brian
Re: External LNB power with the MiniTiouner question please?
>>I just read this - it is a 74HC10 not a 74LS10
Yes. An LS10 won't be very happy running off 3.3v.
Brian
Yes. An LS10 won't be very happy running off 3.3v.
Brian
Re: External LNB power with the MiniTiouner question please?
Ok not sure if this is the problem i have used a 74HCT10 Its a std 5v ic but working on 3.3v so i set the scope up and this is what i got.
Pins 1'2'13 TSerr. 0v ( no picture)
This is pin 8 the output This is pin 9 This is pin 10
Pins 1'2'13 TSerr. 0v ( no picture)
This is pin 8 the output This is pin 9 This is pin 10
Re: External LNB power with the MiniTiouner question please?
That's the problem. The specification is 74HC10. The HCT has a minimum voltage of 4.5V and expects TTL level inputs. It might appear to work but might well give unpredictable results. You are seeing exactly that.
Mike
Mike
Re: External LNB power with the MiniTiouner question please?
Stupid as it sounds i knew every thing was running at 3.3v but used a chip from stock and never gave a thought about its voltage ill get another one ordered and hopefully all will be well.
Well at least its one for future reference if anyone else gets these problems.
Thank you so much MIKE G0MJW,
BRIAN G4EWJ
COLIN G4EML
DAVE G8GKQ
Thanks again
Nigel 2E0NJT
Well at least its one for future reference if anyone else gets these problems.
Thank you so much MIKE G0MJW,
BRIAN G4EWJ
COLIN G4EML
DAVE G8GKQ
Thanks again
Nigel 2E0NJT