New Bipolar Boost TX and Front End

[KingJL]

Another option is to drive the relay from a logic level Mosfet. [ATTACH]47338[/ATTACH]
I use the FDV303 in a lot of 3v3 MPU drive circuits and found it to be very reliable.

Let's go with it!

[Mdtoday]

JL, here is the updated KiCad file for the round Probe switch board.

[ATTACH]47337[/ATTACH]

Another option is to drive the relay from a logic level Mosfet.
I use the FDV303 in a lot of 3v3 MPU drive circuits and found it to be very reliable.

[Mdtoday]

Ok, yes, I see what you are concerned about. I'll make the changes, not a problem.

JL, here is the updated KiCad file for the round Probe switch board.

Probe_switch_round_2.zip

[Mdtoday]

Since we are changing the probe relay circuit, I was a little uncomfortable with the emitter follower configuration. I was concerned that the 1.8K base resistor was not high enough to ,limit the current sufficiently from the 3.3v FPGA pin. In the emitter follower circuit, any increase above 1.8K brings the voltage across the coil below the specification minimum voltage. I propose the following circuit configuration (flyback protection included). It allows use of 5K in the FPGA/base current path and maintains the voltage across the coil within specifications.
[ATTACH=CONFIG]47331[/ATTACH]
I used a 20V 500ma schottky diode for the flyback protection in the schematic, but that can be changed as you see fit.

Ok, yes, I see what you are concerned about. I'll make the changes, not a problem.

[KingJL]

Yes, I had a look at data too and could not find much on it either, so thought I would just include the option in case.
When we are ready, I will order these boards + the power board together
Then Ill have to order some relays.
I haven't done anything more on the main enclosure but will get back to finalising that soon

Since we are changing the probe relay circuit, I was a little uncomfortable with the emitter follower configuration. I was concerned that the 1.8K base resistor was not high enough to limit the current sufficiently from the 3.3v FPGA pin. In the emitter follower circuit, any increase above 1.8K brings the voltage across the coil below the specification minimum voltage. I propose the following circuit configuration (flyback protection included). It allows use of 5K in the FPGA/base current path and maintains the voltage across the coil within specifications.
probe relay.pdf
I used a 20V 500ma schottky diode for the flyback protection in the schematic, but that can be changed as you see fit.

[Mdtoday]

Here is the the layout after the tidy-up.





cheers

Mdtoday

[Mdtoday]

I actually had considered using one in my original design. I could not find any recommendation in any documentation. I suspect that it is internally protected as the 2 energizing contacts are polarized. But in the end... it can't hurt or "better safe than sorry".

Yes, I had a look at data too and could not find much on it either, so thought I would just include the option in case.
When we are ready, I will order these boards + the power board together
Then Ill have to order some relays.
I haven't done anything more on the main enclosure but will get back to finalising that soon

[KingJL]

JL, I have also designed another version of your Probe/coil switch.

A fly-back diode option has been added, if its required...

I actually had considered using one in my original design. I could not find any recommendation in any documentation. I suspect that it is internally protected as the 2 energizing contacts are polarized. But in the end... it can't hurt or "better safe than sorry".

[Mdtoday]

JL, I have also designed another version of your Probe/coil switch.

A fly-back diode option has been added, if its required

It now has 2 pcbs and provides easier assembly with more room for JST connectors and wires.
The rectangular version causes mating connector/wires to be at tight angles in the connector bay..its fine in the main enclosure though.
The 5 pin connector board and probe board is configured with either JST or solder pins in J3 or J4 positions depending which bay the boards are mounted in the housing.





We have 2 options now with this one ...

I will post the Kicad files later along with assembly view

[Mdtoday]

Thanks JL,

A couple of things to tidy up and I'll post the Kicad files later today for you to have a look at and if all looks ok, Ill place an order.

Here are the KiCad files. Power_PCB_Rev2.zip

cheers

Mdtoday

[Mdtoday]

Thanks JL,

A couple of things to tidy up and I'll post the Kicad files later today for you to have a look at and if all looks ok, Ill place an order.
1)The input and output tracks to the switch mode will be changed to rear side of board so the shielding will be more effective.
2) Provisions made for extra filter Cap on output of the MT3608
3) Finish via stitching of the ground planes

cheers

Mdtoday

[KingJL]

I have been busy with testing the power supplies and redesigning the power board for lower noise.

The MT2608 modules have a less than optimum layout, so I have reduced the switching current paths to minimum with an on board circuit and dropped the option for modules

Here is the latest schematic. [ATTACH]47317[/ATTACH], I have used low noise LDO regulators LT1963AEQ which are me-too type available from LT, TI and 2 other manufacturers.

[ATTACH]47318[/ATTACH] still some tidy up to do and then sanity check

[ATTACH]47319[/ATTACH] Enlarged the pads on the battery holder footprint as I had to trim the SMD tags on the actual holder to fit Rev1.00 board. Added 4 mounting holes and removed cut-outs on board sides.

The batteries are now back in series and using 2 LDO linears for 3v3 fixed and 4.5-5v adjustable supplies. JL, I have stock I can send with the boards and will also load some boards some for you too.

Ill do some more work tomorrow and post Kicad files, then order boards after sanity checks.

The switch mode has provision for shield which helps with radiated noise. The TPS7A49 works well as the post regulator for the switcher and is optimised for High PSRR up to about 400kHz, the MT3608 is 1.2MHz and while the test board showed a huge reduction in output noise and PS ripple,it may not be so on the finished board, it should be , but we will see.

They are looking good!! Great work.

[Mdtoday]

I have been busy with testing the power supplies and redesigning the power board for lower noise.

The MT2608 modules have a less than optimum layout, so I have reduced the switching current paths to minimum with an on board circuit and dropped the option for modules

Here is the latest schematic. KingJL_PWR_Rev2_00.pdf, I have used low noise LDO regulators LT1963AEQ which are me-too type available from LT, TI and 2 other manufacturers.

still some tidy up to do and then sanity check

Enlarged the pads on the battery holder footprint as I had to trim the SMD tags on the actual holder to fit Rev1.00 board. Added 4 mounting holes and removed cut-outs on board sides.

The batteries are now back in series and using 2 LDO linears for 3v3 fixed and 4.5-5v adjustable supplies. JL, I have stock I can send with the boards and will also load some boards some for you too.

Ill do some more work tomorrow and post Kicad files, then order boards after sanity checks.

The switch mode has provision for shield which helps with radiated noise. The TPS7A49 works well as the post regulator for the switcher and is optimised for High PSRR up to about 400kHz, the MT3608 is 1.2MHz and while the test board showed a huge reduction in output noise and PS ripple,it may not be so on the finished board, it should be , but we will see.

[Mdtoday]

We are back on track!!!

New baseline for the project is Vivado_Bipolar_PI(8-30-2019).zip
Delete the folder "Bipolar_TX" from your previous project folder... it is replaced by "TX-RX" folder.

[ATTACH=CONFIG]47297[/ATTACH]

That's excellent news JL, well done!

I will download have a look, thanks for sharing.

[KingJL]

New Baseline Design

Well still no joy... I have come to the conclusion that the TX-X ip is too complex with nested out-of-context synthesized ip (TX-RX->AIX->RX->(xilinx configurable CIC ip)) and the synthesized nets get dis-organized. I have to give some thought to this... I have two options:
(1) simplify the RX portion of the TX-RX to just gather the XADC outputs and the interrupt the to upc pull them. Create another ip that receives the samples from the upc and filters them through the CIC which then alerts the upc that a filtered product is available. This has the added benefit of greatly simplifying the TX-RX ip and reducing the communications register set... I am leaning to option 1 ...

We have a new baseline!!! After fighting the issue of the loss of RX interrupts for two weeks, I restructured/simplified the design of TX-RX and RX modules. Now the output from the XADC for each sample is inserted into the communications register set as they are available from the XADC, When sample 3 is inserted, an interrupt is sent to the upc. Interrupts ( the correct number) are being received by the embedded processor. During testing a notification is displayed every 2000 interrupts received. The notifications are occurring once a second as expected.

All testing/debug print statements are conditionally compiled with #ifdef and #ifndef statements. The #define for the different test/debug prints are contained in Bipolar_PI.h. Simply comment/un-comment the appropriate #define to turn on/off the prints. Also major functions of code are conditionally turned on/off with defines in the Bipolar_PI.h.

The next task is to create a filter hardware module so that the embedded processor can forward the RX data and be notified when filter outputs are available.

We are back on track!!!

New baseline for the project is Vivado_Bipolar_PI(8-30-2019).zip
Delete the folder "Bipolar_TX" from your previous project folder... it is replaced by "TX-RX" folder.

Changelog
Change Log.txt