In-depth analysis of T-BOX system solution: wireless connection unit

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In-depth analysis of T-BOX system solution: wireless connection unit [Copy link]

The telematics control unit (TCU or T-BOX) is an embedded vehicle-mounted system that can be used in areas such as wireless tracking and communication of vehicles.

In T-BOX, the wireless connection unit mainly includes the following four modules: GSM/GPRS/LTE, GPS, Wi-Fi and Bluetooth.

Figure-1

1) GSM/GPRS/LTE

GSM/GPRS/LTE are all mobile communication technologies. GSM (Global System for Mobile Communications) is the second-generation mobile communication system, which is what we often call 2G; GPRS (General Packet Radio Service) is a general packet radio service developed based on GSM, commonly known as 2.5G; LTE (Long Term Evolution) is the fourth-generation mobile communication system, which is 3.9G, and LTE-A is 4G.

Their speed levels are as follows: GSM < GPRS < LTE. Usually, these communication systems do not exist separately, for example, Qualcomm processors integrate 4G communication modules. As mentioned above, when encountering an emergency, the call center uses these communication modules to communicate with the car owner.

2) GPS

GPS (Global Positioning System) mainly provides the location coordinates of the vehicle for tracking or navigation. As mentioned in the previous emergency call unit, when encountering an emergency, the call center can obtain the specific location of the vehicle through the GPS module, so as to carry out rescue work in time.

3) Wi-Fi

In T-BOX applications, Wi-Fi is mainly used as a wireless hotspot to connect electronic devices in the car, such as mobile phones, tablets, computers, etc. TI's solutions include SimpleLink Wi-Fi solutions and WiLink 8 solutions.

SimpleLink Wi-Fi solutions rely on microcontroller systems. Microcontrollers only want to add Ethernet functions to send simple status information or receive control commands. Users can quickly start designing without being proficient in RF/Wi-Fi theory, shortening the development cycle. WiLink 8 solutions are used in typical microprocessor systems that require high throughput, performance, and integration, such as hard disk drives, e-books, etc. Their differences can be summarized as shown in Table-1 below:

	SimpleLink Wi-Fi		WiLink
	Wireless MCU (SoC)	Network Processor
Main processor	MCU (Internally integrated)	MCU (external)	MPU (external)
operating system	RTOS /None		Linux/Android/RTOS
Data throughput (MBPS)	<20		100
Supported bandwidth (GHz)	2.4		2.4/5
Integrated network protocol TCP/IP	√
End-to-end IoT security	√
Low power optimization	√
Monitoring certification	√
Wi-Fi + BLE coexistence	√ (BLE external)		√ (BLE+BT integration)
SimpleLink MCU platform support	√
Cloud IoT Support	HomeKit, AWS, Azure, IBM and more		HomeKit
Related Products	CC3200	CC3100	WL1801,WL1805,WL1807, WL1831,WL1835,WL1837

Table-1

WiLink series chips, such as WL1831, can be used in T-BOX applications. The main differences among the six chips in this series are whether they have low-power Bluetooth, TX current size, and operating temperature range. The main differences are shown in Table 2.

	WL1801		WL1805	WL1807	WL1831			WL1835		WL1837
processor	External MPU
Technical Support	Wi-Fi				Bluetooth low energy/Wi-Fi
Data throughput (MBPS)	100
RX sensitivity (dBm)	-96
TX current (mA)	247	247		238		247	247		238
Operating temperature range (℃)	-20 to 70	-20 to 70		-40 to 85		-20 to 70	-20 to 70		-40 to 85
Encapsulation	MOC (100 pin LGA Module)

Table-2

The features of this series are listed below:

• Simple design: RF and power management are integrated, so you can start designing at any time without any RF/Wi-Fi expertise.
• Superior performance: Optimized real-time online profile function; low power mode when powered by battery; high throughput; wide coverage.

4) Bluetooth

There are many reasons for applying Bluetooth technology to the automotive field: good interoperability with smartphones and wearable devices; low power consumption, which can extend the use time in battery-powered situations; the module is small and does not take up too much space in the car; it provides cost-effective solutions for many emerging applications, such as car access control, car sharing, remote parking, etc., which has triggered a new round of innovation in connected devices such as smartphones.

TI's automotive-grade low-power Bluetooth chips include CC2640R2F-Q1 and CC2541-Q1. Their differences are shown in the following table:

parameter	CC2640R2F-Q1	CC2541-Q1
Temperature range	-40°C to 105°C (Grade 2)
Bluetooth Specifications	Bluetooth v4.2+	Bluetooth v4.0
SW upgrades available for future BLE specification updates	√
Supply voltage range	1.8 – 3.8 V	2.0 – 3.6 V
Current consumption @ max RX sensitivity Current consumption @ TX output power 0dBm	6.2 mA 6.9 mA	18.3 mA 18.6 mA
operating system	√(TI-RTOS)
On-chip DC-DC	√
Shutdown current	150 nA	500 nA
Standby current	1 A	1 A
MCU	32-bit ARM Cortex-M3 (48 MHz)	8-bit 8051 (32 MHz)
Embedded Flash/RAM	128 KB + 8 KB cache / 20 KB + On Chip ROM	256 KB / 8 KB
Output power consumption	+5 dBm	0 dBm
Receiving sensitivity	-97 dBm	-94 dBm
Link Budget	102dB	94dB
Encapsulation	Automotive grade RGZ QFN48-7x7 w	RHA QFN40-6x6w
Synchronous connection	Up to 8 (Multi-Role)	Up to 3 (Central to Peripheral)
GPIO	31	twenty three

Table-3

TI mainly promotes CC2640R2F-Q1, and its features are listed as follows:

• Ultra-low power consumption: 1 A standby current enables long battery life and low space usage in automotive modules;
• Excellent RF performance and ultra-long transmission distance: sensitivity up to 97dBm and link budget up to 102dB;
• High reliability: AEC-Q100 qualified, -40°C to 105°C (Grade 2), wettable flank package;
• Flexible platform support: Multi-core SoC with independent application and wireless domains, supporting Bluetooth 4.2 and Bluetooth 5.

TI has corresponding evaluation boards and software support:

• SimpleLink Bluetooth Low Energy CC2640R2F Wireless MCU LaunchPad Development Kit
• SimpleLink CC2640R2 SDK - Bluetooth low energy