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Padmal
@CloudyPadmal
Sounds great. I think we can go ahead with that! :+1:
CyReVolt
@CyReVolt:matrix.org
[m]

This could be interesting for PSLab as well:
https://twitter.com/beriberikix/status/1465041736468611072?t=gA7HwYMINXofCj2kVtqrPA&s=19

(porting libusb to WASM)

Mario Behling
@mariobehling

Dear @/all Please join our weekly open hardware call on Saturday at 17:00 CET / 21:30 IST. Please register at https://eventyay.com/e/1873937b

In this meeting we discuss the progress and next steps of the new Pocket Science Lab version (https://pslab.io), development, firmware, Android app and production questions. If you would like to share updates on other projects you are working on, you are welcome too!

After registering you can click the "Join event" button on the event page and then click on the video room link on the left to participate in the meeting.

RafaelLeeImg
@RafaelLeeImg
I found a power bank charging management chip, supports 1.5A charging and 2A, 5V boost output, IP5206 or IP5305. The price is arount ¥1 RMB. It can replace LTC4040. The LTC4040 is around $5 USD in China. What do you think? The datasheet is in Chinese. I think the chip is widely sold in power bank around the world but it's only used in Chinese made power banks.
Any comments?
Mario Behling
@mariobehling
@RafaelLeeImg Nice. Do you have a link to the component/manufacturer?
RafaelLeeImg
@RafaelLeeImg
Here's the site of the IC manufacturer.
http://www.injoinic.com/product_detail/id/21.html
It just suddenly came to my mind that we can use power bank IC.
Mario Behling
@mariobehling
:thumbsup:
RafaelLeeImg
@RafaelLeeImg
Hi. The USB-to-Serial chip CP2102 I can find, but the price is a little high around $1.7 USD. However I found that PL2303GL is available, the price is half of it. The speed limit is 115200, is the speed enough?
Padmal
@CloudyPadmal
We're running at 1,000,000 baud rate. 115,200 is a bit slow..
RafaelLeeImg
@RafaelLeeImg
OK. Is there any other specific requirement for the USB-UART converter?
Padmal
@CloudyPadmal
Data rate is the key point. Other than that, it's the component count. CP210x doesn't require any crystals etc.
RafaelLeeImg
@RafaelLeeImg
CP2102 QFN24 is out of stock. I bought 1000 pcs of CP2102 with QFN20.
RafaelLeeImg
@RafaelLeeImg
I sent the modified PSlab v6 to manufacturer. I changed nearly all power ICs to make the design able to manufacture.
Now the only blocking things are MCP4728 and MCP6S21 are not found.
Mario Behling
@mariobehling
@RafaelLeeImg Thanks! Curious to learn how it is working. We have a quote of another supplier in China as follows:
MCP4728: RMB 86.000
MCP6S21: RMB 10.800
What do you think about this?
RafaelLeeImg
@RafaelLeeImg
MCP6S21: RMB 10.800 is OK. MCP4728 is too expensive, think about this, we can use even several stm32s to replace this DAC, there is no reason to use that.
Mario Behling
@mariobehling
What price for MCP4728 is within an acceptable range?
RafaelLeeImg
@RafaelLeeImg
I suggest spend no more than 20 on this chip, idealy, no more than 10. Since it's only a 4 channel DAC with with the speed of below 200k samples per second. That's a very ordinary DAC. There is no need to spend much money on it.
Mario Behling
@mariobehling
Correct. In one of the previous orders MCP4728 was 6.00 RMB and now they quote 86 RMB. I wonder if they meant 8.60 RMB.
@RafaelLeeImg I am looking forward to your tests to see if any other components need to be changed.
RafaelLeeImg
@RafaelLeeImg
I already have too many ICs at home. Haha, really a lot.
Mario Behling
@mariobehling
:thumbsup:
Mario Behling
@mariobehling
@CyReVolt:matrix.org @bessman Here is the submission for an online talk on 27th Dec that we discussed today https://pretalx.c3voc.de/rc3-2021-xhain/talk/3BFKMQ/
apoorva-raj
@apoorva-raj
Hey, I'd like to contribute on this project for codeheat. Do I have to buy the hardware to do so?
CyReVolt
@CyReVolt:matrix.org
[m]
News on the rC3 world @mariobehling
https://events.ccc.de/2021/12/20/rc3-was-wie-wo/
Alexander Bessman
@bessman
@mariobehling Do we need to sign up somewhere before the panel discussion? What technology will be used for the call? Eventyay?
1 reply
CyReVolt
@CyReVolt:matrix.org
[m]
https://twitter.com/vthakkar_/status/1102228437140414465?t=f574UuaBASTlPFSWqeORYg&s=19
this is a nice cheat sheet for sending patches via email 📧 👩‍💻
RafaelLeeImg
@RafaelLeeImg
MCP6S21 is hard to find, I may use CAT5171 or MCP4017 to build variable gain amp.
I need to find another I2C DAC to replace MCP4728, too.
RafaelLeeImg
@RafaelLeeImg

Good news: The basic test of the replaced power chips all function normally, including the charging, discharging, power supply with/without the battery. 10V boost circuit, -10V capacitor pump, +6V and -6V voltage source.
I add a button to control the IP5189T power bank IC. Press the button to turn it on, press 2 times to turn it off. The power bank IC will measure the current, if the current is less than 45mA, it will cut-off the output after 40 seconds.

I've replace the MCP6S21 with a MAX5400 digital potentiometer and a TL082 general operational amplifier.
I've replace the 4 channel DAC MCP4728 with 2 two channel DAC MCP4822, if there is no strong synchronization between different DAC channels. I think it's OK because the 4 amplifing circuits after DAC are pretty different, so there may be no requirement for synchronization between DAC channels.
I've add a 74HC4051 to handle the Chip-Select pins which are newly added.

Bad news: I only bought 2 pieces of IP5189 for testing, I checked there are more than 3000 pieces when I chose to test it, but now there are none left. I may need to test IP5219 instead or wait for a while.

The datasheets are here http://www.injoinic.com/product_detail/id/21.html

I need PIC24 chips and a debugger if there are some to further test with modifying the firmware.

RafaelLeeImg
@RafaelLeeImg

Story of Arduino.. https://blog.arduino.cc/2021/12/09/one-board-to-rule-them-all-history-of-the-arduino-uno/

Being a engineer for years, Arduino is not my option in any of my projects. It's comparably expensive, poor-porformance, poor-designed. The true story that they use Atmega MCU is that there space have several thousands of Atmega by coincidence. Not a solid reason. To some extent, we say that Arduino saved Atmel.
The toolchain is poor. IDE is poor, even the default font is ugly for programming.

It has done some help to newbies, but the terminology they used is not accurate in software field. It will make Arduino users harder to understand the development of MCU programming, vice-versa.

They have done nearly none contribution to the electronics and software world outside of Arduino. They could have done better job to let the software community contribute to more general embedded programming.

RafaelLeeImg
@RafaelLeeImg
They tried to hide the compiling and running process, the idea is good, but they have ruined them all. Even incrimental compiling is not enabled by default.
I don't have much experience developing Arduino related projects and whenever I have any better choice, I will not use it.
A good projects shall designed to be good, there should be philosophy under the projects. It's useful when trade-offs are required. Even ESP8266 supports Arduino IDE, Arduino team could have done much better. I didn't see any efforts they made to make arduino more modern, they have used up their luck.
apoorva-raj
@apoorva-raj
Please review my PR
RafaelLeeImg
@RafaelLeeImg
I can compile pslab-firmware with XC16 compiler now, where is the firmware for PSLab v6? Is the branch origin/bootloader working for V6?
RafaelLeeImg
@RafaelLeeImg
Shall I buy a PICkit 3 or 3.5 debugger, is v3.5 better?
Alexander Bessman
@bessman
The bootloader branch contains two folders, pslab-bootloader.X and pslab-core.X. The latter contains the actual firmware.
I use a PICkit3, I think @CloudyPadmal uses the same. No idea what's different in the newer version.
The firmware found in pslab-core.X folder works for the V6, with a few exceptions that haven't been implemented yet.
RafaelLeeImg
@RafaelLeeImg
OK. Good, Then I have a good place to start. I already took a look at the structure of the code. I need sometime to understand it. I didn't find any code related to SPI cs pin selection, that's where the modifications made my me due to the lack of MCP4728.
Alexander Bessman
@bessman
We currently use I2C to talk to the MCP4728, not SPI. That code can be found here: https://github.com/fossasia/pslab-firmware/blob/bootloader/pslab-core.X/instruments/powersource.c
Alexander Bessman
@bessman
I see the MCP4822 has no I2C interface. The SPI implementation is here: https://github.com/fossasia/pslab-firmware/tree/bootloader/pslab-core.X/bus/spi
Alexander Bessman
@bessman
I finally got the TCD1304 to give me something that looks like real data:
Green line is entire sensor exposed, orange completely covered, blue half-covered.
(Is there a way to post images directly in the chat? Drag-and-drop doesn't seem to work.)
Mario Behling
@mariobehling
lR0uPqY.png
@bessman Looks very good. Drag and Drop works for me.