Hi, I only want to comment that I think this is very clever and useful! Looks like great work indeed!
A point of clarification though. Brian, rexcpm is not usable in Tandy 200. Cheers Steve On Wednesday, September 20, 2023, Ken St. Cyr <[email protected]> wrote: > It turned out nice and looks pretty solid (at least in the pictures). I > ordered boards and parts the other day, so I'm just waiting for those to > arrive now. I'll report back and share my experience after getting one > together - > > //Ken > ------------------------------ > *From:* M100 <[email protected]> on behalf of Brian K. > White <[email protected]> > *Sent:* Tuesday, September 19, 2023 10:18 PM > *To:* [email protected] <[email protected]> > *Subject:* Re: [M100] rexcpm battery > > I have repaired my REXCPM and now the github readme includes pics that > show a good way to mount a qwiic connector and where to connect bodge > wires if you want to take on the challenge of such small loose wires > going to such small places. All 4 solder points are at least a > reasonable chip leg, no soldering directly to delicate traces. So the > wires are reasonably robust in the end. You can install & remove the > rexcpm module without straining the wires. I will probably further > secure them with glue sometime later but haven't yet. > > I don't think it's worth it just to get the connector if your original > pins are still intact, even though the connector is more convenient in > the end, but since my original pins rotated and broke their traces > anyway, I had to do a bodge wire repair anyway. And mounting the > connector seems to be solid enough by super-glueing it to the top of a > chip, and by using one of the black versions of the connector which I > think is a material that the glue can stick to easier. The natural > colored ones look like they might be something no glue will stick to. > The black ones feel like they have some glass filler, and can be scuffed > to a rough texture. Seems to be pretty solid so far though I'm not > testing-to-destruction just to find out. :) > single https://www.sparkfun.com/products/14417 > 10 pack https://www.adafruit.com/product/4208 > > My rexcpm is running and working so I can resume testing battery life. > > I think it's safe to order pcbs if you want now. The dupont breakout > cable is a good solution for keeping the REXCPM side of things simple > and stock, and adding the single wire for gnd is easy, reasonably safe > against blunders, and leaves the REXCPM still compatible with it's > original bus board and cable. So the bus board can keep the qwiic > connector. > > I have tested the 102/200 board now too. good to go. I don't have a > pcbway or gerbers up for that yet but will shortly. > > -- > bkw > > > On 9/19/23 04:29, Brian K. White wrote: > > My boards came in and at least the model 100 one works fine. > > > > There's room, but no good way to solder the qwiic connector to the > > REXCPM, so the most practical way to handle the REXCPM side is just > > use the pre-made adapter cable that has female dupont sockets, and > > stick them right onto the original pins. > > > > For the GND wire, you can treat it as optional and leave that wire > > unconnected, or add a single solid-core wire to the big cap for the > > gnd connection. If you use 23 gauge solid core wire, or maybe a size > > or so thicker, the wire is stiff enough to hold it's shape and thick > > enough for a female dupont socket to stick onto it and not fall off. I > > used 23 gauge wire from some solid core ethernet cable and that was > > about perfect. Other common sources, thermostat wire, doorbell wire. > > > > Take a 25mm piece of wire, strip 3mm on one end and bend it sharp 90 > > degrees, strip 6mm on the other end, poke the wire in between the cap > > and the 3 pins and solder the short bent end to the cap. > > > > Then the 4 female dupont wires go like this: > > > > black (GND) -> wire on cap > > red (/WR) -> closest pin to cap > > blue (RAM) -> middle pin > > yellow (RAM_RST) -> furthest pin from cap > > > > > > > > It turns out you have to be very careful not to strain the original > > pins on the REXCPM.. They rotate pretty easily and break the via free > > inside the pcb, and then the traces break. > > > > At one point I was stuffing the gnd wire down from the top in between > > the pin and the cap, and that put sideways strain on the pin. > > > > My REXCPM doesn't work now unless I hold the pins a certain way to > > cause them to make contact. > > > > I have to desolder a few parts to figure out where two of the traces > > go so I can find where to run bodge wires. Fixing the original traces > > right where they broke at the base of the pins is probably too fragile > > now that the vias are moving like that. > > > > Maybe I'll just remove the pins, fix the existing traces where they > > broke, and solder flexible wires instead of pins where the pins used > > to go, and secure the solder joints with glue or epoxy. Hopefully the > > combination of the glue and the flexible wire, and being super careful > > from now on, will be enough to keep the traces from breaking again. > > > > So I think the battery board is fine, and the cable connection at > > least for model 100 is practical enough (I'd prefer a matching > > polarized connector instead of 4 individual wires, but there is just > > no good way to add that tiny connector that won't be too delicate and > > just break in no time) but my rexcpm is out of commission and I can't > > do any further real testing to get real current and voltages etc right > > now. > > > > I did have it fully hooked up and running briefly before I twisted the > > pins. > > > > I can't test the 102/200 board right now, and the pre-made > > qwiic-dupont cable is only 150mm, not long enough to reach all the way > > from the board to the rexcpm. You could add short male-female dupont > > extensions/jumpers, but that's kind of annoying. > > > > For the 102/200 board, really maybe for both boards, maybe it's better > > to just go down to 2 or 3 cells and full size generic 4-pin headers > > instead of the qwiic connectors. > > > > It does work fine for the 100 version though since there is a pre-made > > cable that is long enough all in one piece. > > > > I've updated the github with bom and pcbway links, and gerber zip for > > the model 100 version. > > > > I say it's safe to order the 100 version at least. > > > > The 102/200 version I haven't worked out how best to connect to the > > REXCPM yet. > > > > https://github.com/bkw777/REXCPM_UPS > > > >
