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TCB Dev / Re: Potential OpenPanzer-DA
« on: October 03, 2025, 03:34:53 PM »
One of the things I've been wanting to do for a while, is to get involved with Open-Source projects proper and put my engineering degree to use. I also got this certain cheese-wedge shaped Tank-Destroyer at a very low price that I want to make my own. So this is a bit of a two birds, one stone. And yeah. I do very much enjoy figuring things out and puzzling PCB layouts.
Honestly I got a way easier task at hand than the v1 likely was for you. The ATMega2560 is kind of infamous for giving PCB-designers nightmares. The allocation of pins to peripherals is all over the place, leading to downright cursed routing if you want to make the most out of its peripherals. Judging from the V1: I guess you experienced this first-hand. Compare that to modern microcontrollers where you get increasingly more flexible Port Multiplexers and it is Night vs Day. I also benefit from FET based drivers and Step-Down converter efficiency reducing the need for thermal design.
Result: I don't have to do weird routing like how you had to stitch the Timer2 IR output by going up to a resistor and then down, nor do I have to care about giving components like the Linear Regulator and motor drivers a lot of copper to dump heat into.
Though I do have to deal with some extra components and some EMC considerations like integrating Ferrite Chokes to keep switching noise from getting in/out.
I2C:
You are correct: if i can make the space in regards of free pins i might as well include a JST-SH with Stemma-QT compliant pinout. Worst case scenario: I declare the tiny footprint as DNP.
Smoke/power:
You have a point. The air-pumps are small 6V motors that have been listed as consuming up to 600mA, so they are not too power-hungry. LDO is an option, but I also have a tiny 1A step-down circuit that uses a LMR54410 that might prove a better solution. We have come to a point that a LDO like the MIC29300 can be bigger and more expensive than a Step-down circuit.
ESC:
I'm just gonna let that remain its own thing. As neat as it may be to have it all integrated. It would greatly complicate the programming and deny flexibility. You end up with something like the Clarks. Having to create different designs for different strengths. Stuff like that Scout ESC-Mini NielsD is working on is far more interesting to have.
Sound:
I have mulled over this. Mostly cause there may be a bit of a problem that with the death of both the OP-Soundcard and the Benedini series. The only practical solution is to use a Taigen sound box.
Easiest solution would be to simply update the OP-Soundcard to have an I2S DAC on-board. Which would make it possible to use a Teensy4.0 instead.
In the long run something more purpose-built could be done. You don't really need that much for sound. Just gotta be able to retrieve and mix two blocks of PCM data and output them to a DAC. A task even an AVR chip can do if you give it access to speedy memory. The new ones even have a 10-bit DAC output that could simplify things further. So something that can do similar to the Benedini is possible. Just need a way to get different blocks of PCM data in as fast as possible. Might do some experiments with Flash memory and SD to test the limits. If there is enough processing power available on the main chip, it itself could potentially output sound, though that might be stretching it a bit and add a lot more work in coding...
BUT one rabbit hole at a time... for now I'm just gonna prioritize the TCB and at first probably make due with a Taigen box. Sound experiments and TWI will be on the side when I need to wait or take a break from the hardware side.
PS: My parents hated dutch children's television with a burning passion. So I grew up with british television instead. Result: I've been mistaken for a Brit quite often!
Honestly I got a way easier task at hand than the v1 likely was for you. The ATMega2560 is kind of infamous for giving PCB-designers nightmares. The allocation of pins to peripherals is all over the place, leading to downright cursed routing if you want to make the most out of its peripherals. Judging from the V1: I guess you experienced this first-hand. Compare that to modern microcontrollers where you get increasingly more flexible Port Multiplexers and it is Night vs Day. I also benefit from FET based drivers and Step-Down converter efficiency reducing the need for thermal design.
Result: I don't have to do weird routing like how you had to stitch the Timer2 IR output by going up to a resistor and then down, nor do I have to care about giving components like the Linear Regulator and motor drivers a lot of copper to dump heat into.
Though I do have to deal with some extra components and some EMC considerations like integrating Ferrite Chokes to keep switching noise from getting in/out.
I2C:
You are correct: if i can make the space in regards of free pins i might as well include a JST-SH with Stemma-QT compliant pinout. Worst case scenario: I declare the tiny footprint as DNP.
Smoke/power:
You have a point. The air-pumps are small 6V motors that have been listed as consuming up to 600mA, so they are not too power-hungry. LDO is an option, but I also have a tiny 1A step-down circuit that uses a LMR54410 that might prove a better solution. We have come to a point that a LDO like the MIC29300 can be bigger and more expensive than a Step-down circuit.
ESC:
I'm just gonna let that remain its own thing. As neat as it may be to have it all integrated. It would greatly complicate the programming and deny flexibility. You end up with something like the Clarks. Having to create different designs for different strengths. Stuff like that Scout ESC-Mini NielsD is working on is far more interesting to have.
Sound:
I have mulled over this. Mostly cause there may be a bit of a problem that with the death of both the OP-Soundcard and the Benedini series. The only practical solution is to use a Taigen sound box.
Easiest solution would be to simply update the OP-Soundcard to have an I2S DAC on-board. Which would make it possible to use a Teensy4.0 instead.
In the long run something more purpose-built could be done. You don't really need that much for sound. Just gotta be able to retrieve and mix two blocks of PCM data and output them to a DAC. A task even an AVR chip can do if you give it access to speedy memory. The new ones even have a 10-bit DAC output that could simplify things further. So something that can do similar to the Benedini is possible. Just need a way to get different blocks of PCM data in as fast as possible. Might do some experiments with Flash memory and SD to test the limits. If there is enough processing power available on the main chip, it itself could potentially output sound, though that might be stretching it a bit and add a lot more work in coding...
BUT one rabbit hole at a time... for now I'm just gonna prioritize the TCB and at first probably make due with a Taigen box. Sound experiments and TWI will be on the side when I need to wait or take a break from the hardware side.
PS: My parents hated dutch children's television with a burning passion. So I grew up with british television instead. Result: I've been mistaken for a Brit quite often!