I was hoping v04 would be the last revision so that I can upload it on my GitHub but sadly, there are more ‘improvements’. I am skipping v03 which is no different from V02 except it has a sliding selector switch instead of solderable jumper, and a pair of piggyback connectors. They were meant to connect & control a MP3 player in addition to the board also serving as a power distribution point.
This is version v04A which has a LiPo battery indicator on its left. I am trying out a new IC feature which I hope will work out. I am also very worried about the four 0805 LEDs 1 to 4 (bottom right) which might be too close to each other. So, once I start to solder them, I will know if this is possible or I might have to change to the smaller (and less bright) 0603 LEDs. Anyway, v04B would be the next revision because I need extra solder pads to connect to the Raspberry Pi PICO and also, an extra capacitor for the new IC too.
The HM1160
Long ago, I wanted to put in a battery indicator for Tricorders. It is not screen accurate but man, it would be a good help to tell when I need the batteries recharged or replaced. Most of the IC or solutions require a lot of space due to its additional components. So, after more than a decade (or three), I came across this ‘new’ IC, the HM1160 (made in around 2020?) from HMSemi.com‘s HM116X series. It is basically a single cell lithium ion indicator with a 4 LED output. It can be configured to give a readout when you push the button SW1 or, just let it stay on for continuous display.
Just one small IC with minimal components that displays the status of the LiPo battery. D1 (LED1) indicates the lowest voltage while D4 (LED4) indicate the highest voltage. I am not sure of the 330 Ohm resistor R1.
This is the detection range as seen from the OSHWHub Website. The LEDs would not light up if it detects voltage of below 3.4volts.
The FUBAR
The Board came back from JLCPCB and I was preparing to populate it. However, I spotted some error with the HM1160 component library which I downloaded from SnapEDA.S3.amazonaws. Apparently, the pin #3 and Pin #6 was swapped and this means v04A Board is a reject. That costs quite a bit of money and more importantly, time. I regretted not having to spot the error while designing. At the back of my mind, I did notice the discrepancy but my fatigued mind ignored it.
The sad part about this is that only after sending the design to be made, I spotted the error. The original library part (on the left) shows Pins #3 & #6 reversed. If you observe the image below, LED D1 came out from Pin #6 and not from Pin #3. After correcting this error, I guess I’d have to make v04B now.
The resistor R1 this time is 100 Ohm instead of 330 Ohm as stated in the Datasheet. Looking at the BOM on this OSHWHub Website, the LEDs are green which is great. So now, I am going to use that as reference.
As intended since inception, the Top Panel Board serves as the main power distribution to all the PCBs and also, the Raspberry Pi PICO (which needs 3.3v to function). The v03 which was intended to be the final version, is now superseded by v04A which removes the PCB to PCB connectors and thus the v04A is now much more compact. Soldering would be very difficult unless you have soldering iron with a pencil tip bit or, you have access to reflow soldering. Now, the v04B is to correct the copper trace mistake for the four LEDs (coming from the MH1160 chip due to the wrong footprint) and also, place an additional voltage regulator IC to create the 3.3volts.
This is the GC04-L Greeting Card Voice Module which plays MP3. I am going to say it again later but first, I am going to say it here. The open-flap Tricorders basically has a minimum of three sounds; the opening of the flap ratcheting sound, the TNG Tricorder whine (which will need to loop) and the closing of the flap ratcheting sound. In order to achieve this, the Voice Player needs to be controlled to play the certain files as and when needed. The GC04 however, is unable to do this as its MP3 files cannot be selected. So, for the time being, it is just a proof of concept.
