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May 29, 2023, 11:36:44 23:36


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 1 
 on: Today at 12:54:54 PM 
Started by _Kenny78_ - Last post by _Kenny78_
CountryIT
Notec/c++ programmer
i'm searching for old compiler
it's my job

 2 
 on: Today at 07:45:18 AM 
Started by Catcatcat - Last post by Catcatcat
Hi all!

I decided to share another tool that I developed for myself and use it to design temperature measurement systems using NTC resistors.


NTC resistors are a very cheap component, their feature is that due to their small size they can perform very fast temperature conversions.

At the beginning, I avoided using them because of the complexity of calculating the formulas that are always given in the datasheet for the components. But when I had to take off all the same, I discovered for myself a mechanism that allows even on the slowest MCUs to perform temperature readings almost instantly. Moreover, the conversion accuracy over the entire temperature range is an order of magnitude superior to factory calibrated digital and analog sensors. For this method, there is no need for a stable reference voltage for the ADC and the measurements are independent of the MCU power supply.

The method is that we need to get a table of ADC values for the existing sensor, in the required measurement temperature range.

The whole problem is where to get the RT characteristic for the sensor. Some manufacturers and dealers provide such information for the selected sensor. Can be obtained in increments of one degree, which is sufficient for high-precision temperature measurement. But some are given in increments of 5, or even 10 degrees. Others provide no information at all.

Quite often you have to deal with such a task that there is a sensor, but there is no description for it at all or it is very short.



For which option I suggest the following tools:

NTC constant calculater by Catcatcat.xlsx - a tool for professionals that allows you to restore the sensor resistance table using four control points, convert it to the required step and get the ADC value depending on the circuit used.






Calculation of the ADC table by Catcatcat.xlsx is a simplified tool designed only to convert NTC resistor data into ADC codes. I recommend it if you have a factory temperature sensor resistance table with a step that suits you completely.






NTC_sensor library for temperature measurement.



If you are interested in more details, you can read here, use Google translator. Attached are the main tools, the library can be downloaded from my website.





 3 
 on: May 26, 2023, 12:12:22 12:12 
Started by anotherandrew - Last post by yahoo
I'm not really interested by this subject. My second Chinese car radio stopped working after another cold winter here. So, I decided to buy another one cheap radio without CAN decoder and the more complex wiring set, expecting they are universal and I can attach my old CAN decoder box to the new radio. No, they are not the same and my old box was not in the list of supported manufactures and models. So, I had to buy a new one from a manufacture and model seen in the setup list in the radio menu.
You mention Raise, this appear to be more popular brand at the moment and the connector pinout is shown on the attached picture (valid at least for the Toyota models). You can see that in addition to the CAN bus, the decoder is controlling the reverse camera voltage, reads the steering wheel keys and add special protocol commands for them in addition to the decoded CAN bus packets.
If you have a logic analyzer, you can scan the CAN bus and the decoder output at the same time, and to see the relation between the CAN packets and the UART data. For CAN, there is enough information for the data, so one by one you will see how they are decoded. For the reverse direction you will need a car radio with a proper setup for this decoder box and to try to control the AC functions or something else and to see the UART commands to the decoder. I postponed that exercise for later when I have time. I really don't need it when almost everything is controlled by my radio. And with the addition to the bluetooth adapter, I have access to all service information and sensors inside the car, to read the trouble codes way before they appear, etc.

 4 
 on: May 26, 2023, 03:22:21 03:22 
Started by anotherandrew - Last post by anotherandrew
I have device like thsi too; unfortunately what I am searching this does not work as infotainment CAN does not appear on OBD port, or at least I am not able to convince the OBD gateway to forward infotainment to OBD for bluetooth scanner to see.

I have CAN commands to turn on and off amp and adjust volume. I was hoping I could make the android radio send UART command to this chinese "Raise" CAN module. this is why I seek that UART protocol. Right now I have atmega and spi CAN module which controls dynaudio amp, but it is not as slick as I want. Thank you for this information, it is nice to see others doing similar things. :-)

 5 
 on: May 26, 2023, 01:33:41 01:33 
Started by anotherandrew - Last post by yahoo
From the CAN bus side you will find many information for the packets used in each car model. But from the UART side each decoder box uses unique serial protocol and when you connect one can bus decoder you have to setup the car radio which manufacture is the decoder, and which model from this manufacture. I see about 30 manufactures with 10-30 models each. They are not equal as protocol so it will be hard to find exactly the protocol for your decoder box.
I started the other way. I bought one universal decoder with bluetooth interface, well documented, and with many phone software for it, so I can make whatever I need, no need to reverse engineer anything:
https://vi.aliexpress.com/item/1005001287644836.html

 6 
 on: May 26, 2023, 01:01:56 01:01 
Started by anotherandrew - Last post by anotherandrew
thank you but no, I want to know if I can send arbitrary can messages. I have the vw tdi vehicle (b7 body, 2015 passat model year) with dynaudio factory amplifier. it can only be power on and off by CAN. I sniff and see the messages (and volume up down and so on) and can make it power on now, but would like to control with custom android app through gateway. I ask chinese vendors but nobody wants to help so I hope maybe peopel here have some document.


 7 
 on: May 26, 2023, 12:05:06 00:05 
Started by anotherandrew - Last post by yahoo
If you just need to use the steering wheel keys, there is no need to use the CAN bus decoder at all. All these car radios have KEY1 and KEY2 lines on the black power connector and you can connect the analog key wires directly and then to teach the radio for each key what is the resistor value.
First I did it like that and it worked. But unfortunately for my RAV4 there were 3 key lines and the radio support only 2 lines. So, finally I bought CAN decoder. In fact, there is nothing to do with the CAN bus, just KEY1, KEY2 and KEY3 are connected as wires to this CAN decoder and it scans the keys and create serial packets for each key press and release.
The real CAN bus information is related to the door switches, A/C control, etc., which is not really needed.

 8 
 on: May 25, 2023, 09:20:38 21:20 
Started by anotherandrew - Last post by anotherandrew
Hello friends. Many chinese android car radios have a optional small box that connects to car CAN bus and gives simple serial UART to this radio. example is https://www.aliexpress.com/item/1005002569086079.html.

I can see UART protocol and there is some detail. example

2E 20 02 01 01 DB or 2E 20 02 02 01 DA

for volume up and down. The base protocol format, checksum and etc is understood, but there is lots of messages that I cannot find detail for.

Does someone have full protocol for these? I see some reverse of java android apk on xda-devs and github which detail some but not all.

 9 
 on: May 24, 2023, 09:38:58 09:38 
Started by Noks_st - Last post by Noks_st
Countrychina
NoteI am a software engineer and also a hardware developer. My hobby is the development of ventilation control systems for computers, mini PCB manufacturing control systems at home, I am fond of quadrocopters (I repair and write programs for them).
I want to join the community (maybe I will be useful in some way)

 10 
 on: May 23, 2023, 11:13:04 23:13 
Started by Poty - Last post by Parmin
Looking through my past work, I found that rather than standard serial transmission, I tend to use a modified Manchester coding to carry the signal across with an old 315 MHz transmitter and receiver.

I used 15ms of high signal as a "1" and 5ms as "0" and read the code at 10ms time slot.

I would send $AA as preamble then a series of codes to ensure that the right transmitter goes to the right receiver.
Then a short payload of not more than 10 bytes.

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