Design of PIC Single Chip Microcomputer to Realize Intelligent Control of Nursing Machine

With the intensification of the aging process in our country, there exists a kind of “vulnerable groups who have been bedridden for a long time” because of the loss of self-care ability in today’s society, especially those vulnerable groups who are almost unconscious. They need to be taken care of for a long time, especially their Cleansing of urine and feces. However, due to the large number of vulnerable groups, shortage of nursing staff and high nursing costs, the contradictions in family care of these vulnerable groups have become increasingly prominent.

With the intensification of the aging process in our country, there exists a kind of “vulnerable groups who have been bedridden for a long time” because of the loss of self-care ability in today’s society, especially those vulnerable groups who are almost unconscious. They need to be taken care of for a long time, especially their Cleansing of urine and feces. However, due to the large number of vulnerable groups, shortage of nursing staff and high nursing costs, the contradictions in family care of these vulnerable groups have become increasingly prominent. At present, the long-term bedridden patient’s toilet cleaning and nursing machine on the market is relatively complete in terms of “intelligent care”. It has functions such as automatic identification and recycling of urine and urine, warm water cleaning and automatic drying, which meet the requirements of “humanized” care. But in the process of use, special “accompanying staff” is still needed. For most modern families, this will be a heavy burden, no matter from human or financial resources, and it also limits the use of toilet cleaners in the family. Therefore, the society urgently needs a new type of toilet cleaning and nursing machine that can realize the “unmanned care” function on the basis of the existing nursing function. This article uses PIC18F87K22 single-chip microcomputer as the main controller of the nursing machine, and uses the Siemens GSM module TC35i to send the alarm information of the nursing machine in the form of “mobile phone SMS” to the mobile phone of the set bed patient guardian in real time. At the same time, the guardian can also use “mobile phone SMS” Send commands in the form of “” to remotely control the operation of the home nursing machine, innovatively realize the “unmanned care” function of the family long-term bedridden patient’s urine cleaning nursing machine, which will largely solve the problem of the caregiver of the family of long-term bedridden patients in our country. Social problems such as shortage and high cost of care are urgently needed to be solved.

1 System composition and working principle

The system is mainly composed of PIC microcontroller main control board, keyboard and Display module, sensor/transmitter module, actuator module, GSM communication module (TC35i) and user mobile phone. When the system is working, the PIC microcontroller will patrol the nursing machine’s water temperature, air temperature, flow rate, the lower limit alarm of the clean water bucket liquid level, the upper limit alarm of the dirt collection bucket, and the leakage detection alarm every 500ms. When an alarm occurs for a certain detection parameter, the nursing machine will not only send out the corresponding sound and light alarm prompt information, but also send the alarm information through the GSM module in the form of “mobile phone text messages” to the guardian’s mobile phone set by the program, prompting the guardian in time Go home and deal with it.

2 System hardware design

System hardware includes power module design, PIC microcontroller main control board circuit design, button design, LCD display design, sensor/transmitter circuit design, voice circuit design, GSM communication module circuit design, and peripheral drive actuator circuit design.

2.1 Chip selection of one-chip computer

Since the MCU and the GSM communication module (TC35i) communicate through the serial port, considering that the ZigBee module will also need to communicate with the serial port in the future, an MCU with at least two serial ports is required; the system needs to collect a total of 10 detection parameters such as air temperature and water temperature ; In the warm water washing and warm air drying process after the defecation is finished, multiple timers are also needed; the motor speed needs to be controlled by the PWM method. Considering the above requirements, this system uses Microehip’s PIC18F877K22 single-chip microcomputer, which integrates 4KB SRAM, 128KB EPROM, 69-bit I/O, 2 enhanced EUSART, 24 channels of 12-bit A/D converters, and 5 16-bit timer, 7 CCP modules and 3 ECCP modules, its resources fully meet the needs of the system.

2.2 Sensor/transmitter interface design

The sensors used in the nursing machine include the detection of parameters such as air temperature, water temperature, water flow, urine and urine detection, the position of the collection bucket, the upper limit position of the dirt in the collection bucket, and the lower limit position of the liquid level of the clean water bucket. The stool adopts the principle of infrared light transmission, combined with the absorption of infrared light by the stool components and the blocking mechanism to determine whether there is stool discharge; when urine, it is determined whether there is urine discharge by analyzing the change in the capacitance of the collection seat by the urine. These sensors are sun cleaning equipment Co., Ltd. specially developed non-contact urine detection sensor. The wind temperature and water temperature sensor adopts the new thermistor PT3M-K51F-BLT1 sensor, which is suitable for measuring wind temperature and water temperature. There are two detection sensors for the position of the dirt in the collection bucket, one is the “high position” detection sensor, and the other is the “extreme position” detection sensor. When the dirt position reaches the “extreme position” alarm, the system automatically stops the processing of urine and feces , To prevent the dirt from overflowing.

2. 3 voice interface circuit design

When an alarm occurs, a corresponding voice prompt is required. The voice part uses a special voice processing chip WT588D-20SS, which is powerful and convenient to use. In addition, a special memory TS25L-16AP is also set up, which has 16M NOR Flash, which can well complete the voice prompt function by cooperating with the voice chip.

2. 4 LCD and keyboard interface circuit design

In order to meet the needs of manual control of the nursing machine, a special keyboard is designed. The interface between this keyboard and the CPU adopts an 8-bit I/O line parallel port input and output mode. LCD display adopts RT12864 graphic dot matrix liquid crystal display module, which can conveniently realize real-time display of detection parameters and control parameters.

2. 5 GSM communication module circuit interface design

2.5.1 Introduction to TC35i module

The TC35i module is an industrial-grade GSM module that supports short message service (SMS), data communication and voice communication. It consists of a power supply part, a GSM baseband processor, a FLASH flash memory, a radio frequency part, an antenna and a ZIF (zero insertion force) connector And other composition (Figure 4). The baseband processor is the core of the TC35i, which mainly processes the voice and data signals in the GSM terminal, and covers all the analog and digital functions in the cellular radio frequency equipment. The TC35i module has 40 pins, which are led out through a ZIF connector. These 40 pins are divided into 5 categories by function, namely power supply, data input/output, SIM card, audio interface and control.

2.5.2 TC35i module interface circuit design

The interface of TC35i with PIC one-chip computer and SIM card is finished through ZIF connector, as shown in Fig. 5. The main pins used by the ZIF connector in this system are as follows: Pins 1 to 5 are the working voltage input terminal VBATT+ of TC35i, the recommended voltage is 4.2VDC, and pins 6 to 10 are power ground (GND). The 15th pin is the start pin IGT (Ignition), active at low level. The external transistor Q1 of this system is connected to the I/O RC5 pin of PIC18F87K22. When RC5 generates a high level greater than 100ms, the start pin IGT is connected to GND. Become low level, start the GSM module. The 16th to 23rd are data input/output, which are DSR0, RING0, RXDO, TXD0, CTS0, RTS0, DTR0 and DCD0. The data input/output interface of TC35i is actually a serial asynchronous transceiver, which conforms to the ITU-T RS232 interface standard. It has fixed parameters: 8 data bits and 1 stop bit, no parity bit, optional bit rate between 300bps~115kbps, default 9600, support standard AT command set. In this system, only RXD0 and TXD0 are connected to the RXD and TXD pins of the PIC microcontroller, that is, the communication between the microcontroller and the TC35i is completed through these two serial ports. TC35i uses an external SIM card, the 24th to 29th is the SIM card lead CCDET2 pin is connected to the CCIN pin of ZIF, used to detect whether the SIM card in the SIM card holder is inserted properly, if it is inserted, the CCIN lead The pin is high, otherwise it is low, so read the CCIN pin level of ZIF through MCU programming to judge whether the SIM card is ready. CCIO is a serial data line, which completes the data input and output of TC35i and SIM card. The 32nd foot is the control foot SYNC, the function in this system is to indicate the working state of TC35i.

3 System software design

3.1 System main program design

The system main program flow chart is shown as in Fig. 6, the software programming adopts MPLAB V8.63 to realize, the compiler adopts HI-TECHCCompiler.

After power on, firstly initialize the single-chip computer and GSM module respectively, and then perform button scanning and processing, enter the default automatic operation mode of the nursing machine, and automatically perform data collection and processing. When an alarm occurs, in addition to the corresponding processing, the alarm information is automatically sent to the patient’s guardian’s mobile phone in the form of “mobile phone text messages” through the GSM module, and the guardian can also send commands in the form of “mobile phone text messages” to remotely control the home The operation of the nursing machine realizes the “unmanned care” function of the nursing machine.

3.2 GSM short message processing program design

GSM short message transmission is essentially a process in which the microcontroller sends a short message to the guardian’s cell phone through AT commands. The TC35i short message module has two working modes, which are set by the “AT+CMGF=n” command, n=0 is PDU mode; n=1 is text mode. Since the data sent and received by this system are based on English alarm conditions and command words, n=1. AT+CMGS is the selected message service. The following takes the “Dirty Full Alarm” alarm as an example to illustrate its realization process through the program.

4 Conclusion

This design innovatively realizes the “unmanned care” function of the household long-term bedridden patient’s urine and stool cleaning nursing machine, which will largely solve the urgent problems of the shortage of family caregivers and high nursing costs for long-term bedridden patients in our country. Good products that benefit disadvantaged groups and improve the livelihood of society and people have broad market application prospects.

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