Model 3的PET钥匙和Security Controller
Model 3的PET钥匙和Security Controller
现在卖车，要有卖点要从客户角度来思考，要营造一些高级感。这方面特斯拉玩得特别溜，绑定特斯拉APP的手机，带着手机靠近车门即可打开车门、坐进车里就可以把车开走，关门离开车之后过一段时间车就自己上锁。或者使用很有特点的Key Card，给人身份感的接入方式，这事本质和我们的PEPS差不多，就是不用给钥匙换电什么的了。我们接下来通过原理图来看一下这个Security ECU的设计。
整体概览
传统的无钥匙进入&一键启动，PEPS（Passive Entry & Passive Start，）需要车外的定位，通过门把手的低频天线来实现；进入到车里面之后进行启动、动力防盗认证，需要车内的定位。Model 3为左右B柱各1根、车内1根共3个蓝牙的模块，然后做了两个RF读卡器（一个整合在B柱里面，一个整合在Security controller里面）
Tesla provides a key card that communicates with Model 3 using short range radio-frequency identification (RFID) signals. The key card is used to "authenticate" your phone to work with Model 3 and to add or remove other key cards, phones, or key fobs.
如下图所示，这包括BCM给一路高边开关给这个BLE Driver进行供电，然后一路独立的CAN通到Security ECU。
这个Security ECU主要承担分别读取三路BLE读卡器的CAN数据，然后处理完发送给Vehicel CAN总线，有两个Security ECU（A&B）进行读取和发送。
这个ECU的连接器之前冬瓜也写过，我这边根据这个原理图重新理了一下。如下所示：
Security ECU内部
通过美国的官方网站可以找到这个部件的内部图片，我搬过来，大家可以参考下，我没仔细拆过这个部件，不过根据叙述，这个Security controller的功能主要是在驾驶的时候确认这个钥匙在位置上，所以也叫Central Security Controller，具备读NFC卡和蓝牙的功能。
1）正面
2）反面
反面的主芯片看不清，这里的数据都是通过这个主芯片处理完再发出去。
这个防盗机制，也在特斯拉给NHTSA的信息里面有所涉及
备注：Passive entry transponder (PET)就是这个Key 钥匙
Tesla explained that its antitheft device will have a two-step activation process with a vehicle code query conducted at each stage.
The first stage allows access to the vehicle when an authorization cycle occurs between the PET and the Security Controller, as long as the PET is in close proximity to the car and the driver either pushes the lock/unlock button on the key fob, pushes the exterior door handle to activate the handle sensors or inserts a hand into the handle to trigger the latch release.
During the second stage, vehicle operation will be enabled when the driver sits in the driver’s seat and has depressed the brake pedal. The driver can then move the gear selection stalk to drive or reverse. When one of these actions is performed, the security controller will poll to verify if the appropriate PET is inside the vehicle. Upon location of the PET, the security controller will run an authentication cycle with the key confirming the correct PET is being used inside the vehicle.
第二阶段
Tesla stated that once authentication is successful, the security controller initiates a coded message through the gateway.
蓝牙和NFC读卡器
这个蓝牙和NFC读卡器是被整合到B柱里面的，整体的效果如图：
内部的照片如下图所示，工作在 13.56MHz 频率，主芯片是ST的ST25R3915，一款车规级 RFID读卡芯片，如下图所示
小结：这套东西整体的成本也不贵，怎么弄着弄着取代了原有的钥匙