|
This is neither RFID nor IC card, the technical routes are different.
To be honest, the design concept of PKE (keyless entry system) comes from the combination of traditional central control remote control and TPMS (tire pressure monitoring system) subsystem technology, at least I think so.
I have designed many versions of these two systems in the early and mid-2000s. Among them, TPMS encountered a huge obstacle that was difficult to overcome, namely the power supply problem mentioned by the original poster, and theoretically there is no way to solve it with linear thinking. Therefore, the only way to solve this problem is to use nonlinear thinking.
At that time, I wanted to use the energy feeding idea of passive contactless IC card to try to solve the problem, but the energy feeding distance was far, which had to reach the meter level, and the influence of large metal objects on the vehicle had to be solved. The energy requirement was not high, and it was enough to trigger the interrupt of MCU by a level change. The MCU at that time could be awakened by external interrupts, and the sleep power consumption was fully able to meet the requirements.
The technical route I chose was the 125KHz contactless IC card system, which could make use of existing resources, make experiments easier, and 125KHz is much less affected by large metal objects than MHz-level signals. However, given the extremely high requirements for volume, weight, and power consumption of the aftermarket TPMS system, I found that this technical route must be in the form of an integrated circuit to meet the requirements, and no existing devices could do it, so the project was eventually scrapped.
The second year after the project was discontinued, I saw a piece of news online that Atmel would launch a wake-up chip dedicated to TPMS. I remember that the press release mentioned that it would use a 400KHz signal, and the technical route was exactly the same as what I had imagined. Because I had many projects to do, I never touched the TPMS system again. Later, I made a special effort to learn more about it and found that the frequency used by the wake-up system was simply 125KHz.
As for the PKE system, its working condition is completely similar to TPMS. In order to extend the battery life, the 125KHz wake-up technology of TPMS can be used directly. I just checked and found that there are also 315KHz ones. In addition to the original Atmel, NXP, Micro Chip (through the acquisition of Atmel) and others also have related chips. Given the market size, it is estimated that there should be a dedicated chip that integrates the wake-up system, MCU, and ISM transmission circuit. If you are interested, you can check it out.
| 
提升卡
变色卡
千斤顶