Yet another MK14 tape interface (ESP32).

[SiriusHardware]

For Colin's hypothetical connector / bridge board the most useful design would be:

Double sided PCB with 32 0.1" spaced contact fingers on the top side of the front and rear edges and 32 0.1" spaced contact fingers on the bottom side of the front and rear edge, so that both edges, front and rear, look like the edge connector on the rear of the MK14.

32 tracks on the top side crossing from each top side front edge contact to its top side counterpart on the rear edge, and 32 tracks on the underside joining the 32 contacts on the underside front and rear edges to make a double sided 2 x 32 way edge to edge joiner.

In the middle of this PCB, halfway between the front and rear, a 32 x 2 IDC pin row connector. Each of the 64 tracks visits one of these pins on the way from one edge to the other

Colin takes this PCB and slides a 'conventional' 32 way edge connector over the front edge contacts and solders the connector's leads to them on the top side and bottom side. He plugs that into the issue VI, and he slots the Realview onto the rear edge contacts. Finally, he connects the M5 stick to the relevant pin row connections.

Tim on the other hand takes the same PCB, but on his he puts a DIN connector on the front edge to match the one he has on the rear of his issue VI, and again slots his Realview onto the rear edge contact fingers.

[SiriusHardware]

the input to the SGM6603 is fed from 'IPSOUT' on an even-more obscure / complex AXP192 Power Management Unit IC.

It all seems to add up to this: Even if you can apply +5V to the 5V terminal on the Grove connector without potentially causing damage (which I am still not confident about) there seems no point in actually doing so since it won't power anything.

On the contrary, the +5V from the M5 will try to power up the 5V supply of the MK14 if the M5 is powered up but the MK14 is not.

[Silvester]

Agreed, I recently had a look at M5stick schematic to understand Grove/Dupont power arrangement.

BTW when I picked up M5stick I also got useful pack of Grove to male/female Dupont : https://thepihut.com/products/m5stac...cables-5-pairs

[coolsnaz2]

Photo showing my M5 Stack connection to the RealView VDU card. Currently I supply my MK14's with 5v, so it is safe for me to pick up the 5v supply for the M5 devices from pins 1 to 3 of the MK14.

The 2nd photo shows the accessories I have used during development, 3.96 unit, Proto Hat and Grove to 4 pin connector. I have used the M5Stick grove connector to power the unit, and the top connector with a Proto Hat. I never connect the usb cable at the same time. Applying power from the MK14 keeps the M5Stick charged and the RTC correct, but you do need to remember to turn off the M5Stick when you turn off the MK14.

Currently I find using the M5Stack Atom Lite the best option at home, and only intend using the M5Stick away from home. The Atom Lite is being powered from the MK14 via the Grove connector.

I will publish a document soon explaining the Fast Loader protocol, so that anyone can develop their own Fast Loader programs on other devices, Arduino, Raspberry Pi, PET, BBC or other.

[SiriusHardware]

Silvester and I are wondering whether it is OK or even productive to feed +5V into the 5V terminal on the 4-pin Grove connector - it's not too clear from the above whether this is something you do or you avoid doing, but the destructions I copied from the (not yet final) manual for the M5StickCplus version of your loader seem to suggest that this is a connection that should be made. (Post #195).

Could you clarify what the actual position is in that respect?

In your second image above you show that the cable loom for your Atom modules intentionally has the +5V wire removed at the module end, and the M5Stick cable looks like it is coming out of the 8-pin end of the module via a proto-hat. Silvester reckons it is actually OK to feed +5V into the 5V - in terminal there but not into the 5V terminal on the 4-pin Grove connector, which looking at the schematic is an output only?

[Realtime]

Originally Posted by SiriusHardware

In reality you only need four, possibly only three pins soldered to the connections for 0V, Sense-B and SIN, (and maybe +5V) but a single pin soldered to a single pad on the exposed side of the PCB would soon get knocked off.

Agreed and here's a photo of my set up with the Atom Lite solution (thanks Coolsnaz2 ). I've hacked into the analogue tape interface module but all it's doing is picking up SIN, SENSEB, 5V and GND (I still use the old tape interface on occasions). There is a track to cut on the Tape Interface PCB so if you want more info Colin, let me know.

Alternately I would be inclined in the first instance to just wire the 4 signals to the back of RealView to a local Grove 4 pin floating socket. If at some point you want to expand to having the full bus broken out then it's easy to remove.

[SiriusHardware]

Just a reminder about what rails and signals are where on the rear of the 'Slothie' issue VI MK14 PCB, and therefore also on the rear studs of the edge connector on RealView, looking at the studs from the rear of the PCB.

The essential connections are 0V, Sense-B and SIN. +5V is not actually necessary as long as the module has plenty of battery charge to run on but if you do take +5V from the MK14 to the module then IMO it needs to go the the '5V In' pin on the 8-way connector on the M5StickCPlus module, not to the 5V connection on the 4-way Grove connector which is an output, not an input.

[coolsnaz2]

SiriusHardware: I agree that if feeding power into the M5StickCPlus module then the 8-way connector should be used, using a Proto Hat or equivalent. Applying 5v to the grove 5v o/p does not seem to do any harm, but also does not do any good, as the internal battery is not charged from the grove connector. The 5v Out Boost circuit inside the M5StickCPlus is tolerant to 5v being applied to its output. I will update my M5StickCPlus instructions accordingly.

The Atom Lite is different, the 5v Grove pin is electrically connected to the 4-way connector. So using the Grove connector is the most convenient way to connect the Atom to the MK14, but you could choose to use the 4-way connector instead with the Atomic DIY Proto Kit.

[SiriusHardware]

Thanks for the clarification.

Connecting the MK14 +5V rail to the Grove +5V out may not harm the onboard regulator on the M5StickCplus in that way, but it does create an uncomfortable situation whereby if the MK14 and the M5 are connected that way and the M5 is powered up but the MK14 is not, the M5 will try to power up the whole of the MK14 via that little regulator.

I think it is a situation best avoided.

[SiriusHardware]

I agree that if feeding power into the M5StickCPlus module then the 8-way connector should be used, using a Proto Hat or equivalent.

If the MK14 was connected entirely to the 8-way connector on the Proto Hat side, does that mean that the I/O pins used for output to the MK14 would need to be changed from G32/G33 to (I would guess) G25 and G26?

[coolsnaz2]

If the MK14 was connected entirely to the 8-way connector on the Proto Hat side, does that mean that the I/O pins used for output to the MK14 would need to be changed from G32/G33 to (I would guess) G25 and G26?

SiriusHardware, your guess is correct, I will PM you with options.