Feature #5892
opendesign/build ext clock input board for PlutoSDR Rev.B
70%
Description
We have a number of plutosdr devices at sysmocom, unfortunately all of them still RevB which unlike current RevD has no external clock input. Most of our use cases require a proper reference clock input, so I thought it might be a good idea to build a small board which contains the LTC6957HMS-3#PBF based input circuitry that was added in RevD. This circuit ensures that any square or sine clock can be used, at proper 50 Ohm impedance, over a wide range of levels.
The ext in / ext out ports should be SMA connectors, so that the resulting PCB can be panel-mounted by bulkhead-mounting those two SMA connectors to a face plate of whatever enclosure we're putting the plutosdr into.
The interconnect between the clock board and plutosdr can be made via u.fl as shown in https://coherent-receiver.com/wp-content/uploads/2018/01/umc-pluto-site.jpg
https://wiki.analog.com/university/tools/pluto/hacking/hardware
Files
Checklist
- schematics
- pcb layout
- order pcb prototypes
- order parts
- assemble prototypes
- test prototypes
- test prototype attached to plutosdr RevB
Updated by laforge 10 months ago
- Checklist item schematics added
- Checklist item pcb layout added
- Checklist item order pcb prototypes added
- Checklist item order parts added
- Checklist item assemble prototypes added
- Checklist item test prototypes added
- Status changed from New to In Progress
- % Done changed from 0 to 20
schematics finished; components arranged on 40x40mm PCBA. routing still pending
Updated by laforge 10 months ago
- File plutosdr-revb-clkin.png plutosdr-revb-clkin.png added
Updated by laforge 5 months ago
ah, ok. rather obvious: SD1/SD2 (shutdown1/shutdown2) are both pulled high using R1 (R85 in original schematics), but as we don't have the Q3 FET that can (under digital control) pullt them down, they are permanently in shutdown.
We should replace R1 to VCC with a 0R to GND.
Updated by laforge 5 months ago
- Checklist item test prototype attached to plutosdr RevB added
- Checklist item test prototypes set to Done
- % Done changed from 50 to 70
laforge wrote in #note-8:
We should replace R1 to VCC with a 0R to GND.
and it works. I've reworked the prototypes and changed the design in https://gitea.osmocom.org/electronics/osmo-small-hardware/commit/dbd53d6df52089065254c2a5830343b423d3d5b8
Updated by laforge 5 months ago
- File pluto-revb-orig.jpg pluto-revb-orig.jpg added
- File pluto-revb-xo_removed.jpg pluto-revb-xo_removed.jpg added
- File pluto-revb-pad_removed.jpg pluto-revb-pad_removed.jpg added
- File pluto-revb-copper_scratched.jpg pluto-revb-copper_scratched.jpg added
- File pluto-revb-ufl.jpg pluto-revb-ufl.jpg added
Updated by laforge about 2 months ago
- Status changed from In Progress to Stalled