Mike - I can confirm that the address is 55 hex.? I used the Si Lab part number look-up, and the I2C address scanner routine.? This is the specific part:
The only output I see is the clock + and clock - on pins 4 and 5.? In this circuit, Clock + (pin 4) is used and 5 is left floating.? Applying the Rigol's probe across 4 and 5 shows the same 100 MHz output as that seen from clock + and ground.? The Si 570 block diagram shows a crystal inside, but there doesn't appear to be a way to probe it from outside the case.? Is there a way to check the function of the part?? The software sets the the start-up frequency to 56.32 MHz, and later moves it to 14.5 MHz.
I thought this device outputs a square wave, and I expected the software to command the Si570 to change freqs when the display changes.? So far, neither of those things happens.? I don't know if I got a bad part, killed it somehow, or have a library problem.? I guess I'll start with libraries.? A number of others have built these things and I've not found any suggestion that they didn't 'just work'.??
Andy, KG5RKP
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On Tue, Dec 12, 2017 at 03:02 pm, Michael Hagen wrote:
I have made several signal generators with 2 different PCBs I designed.? Both stand-alone with level shifting.
The big one uses the SI part with 8 Clocks, I call it "Lotsa Clocks".? It has optional I2C address bit.? And 8 Clocks.
I got all my SI parts from Mouser.? Mine respond at 0x60 or 0x61 ?? I have seen them run at the outputs with crystal not correctly connected.? I have stopped using the Tiny crystals because of soldering problems.
Check for 25 MHz small sin wave on the crystal pins.? One pin has a larger sin wave than the other.? I have made a sketch that runs one or the other or both SI parts on 0x60 and 0x61.? I have bought dozens of them, always have seen those 2 addresses?
73's
Mike, WA6ISP
On 12/12/2017 12:48 PM, AndyH wrote:
Hey folks,
? ?The executive summary is that I've assembled an Si570 generator for a Sweeperino (prereq for my scratch built ?BITX) and it's emitting a 400 mV p-p sine at 100 MHz.? I cannot adjust the frequency.? I have no idea what's happening.
? ?Details...? I verified details of the Mouser-sourced Si570 from the Sil Labs database.? The address is verified (0x55) and I can talk to the Si570 with an I2C scanner and Farhan's code (as well as the Razzie code).? Voltages are good, the layout was inspired by Farhan's build as well as the builds documented by Tony Fishpool and published in Razzie (June, 2016).? Adjusting the tuning pot makes the numbers change on the LCD. There's a light square wave on the Rigol display when the frequency is actually changing.? I can't collect this signal by probing the Arduino or the comms or power pins - its only present on the output of the Si570.
? ?Does this mean anything to the Si570 experts?
? ? Thanks,
? ? ?Andy, KG5RKP
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Mike Hagen, WA6ISP
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