Dyeing automation controller based on S12X dual-core microcontroller

In the textile industry, dyeing is an important production link for textile coloring. Fabric dyeing requires that a certain heating rate or cooling rate must be followed during different heating and cooling processes. In addition, different dyes and textiles require different temperature change curves for dye liquor [1]. Figure 1 shows a typical step-by-step heating process in actual production. The process is divided into three sections: the first section has a holding temperature of 80 °C and the number of forward and reverse rotations (passes) required during the holding period is 1; the second section has a holding temperature of 90 °C and 1 pass; the third section has a holding temperature of 135 °C and 2 passes.

For a long time, the dyeing process has been completed by general temperature controllers in combination with manual operation. This manual control dyeing method based on general temperature controllers is difficult to ensure the strict temperature increase and decrease rate required by the process, and different workers will also have differences when operating the same process requirements, thus affecting the quality and output of the product. At the same time, the temperature and humidity in the dyeing workshop are high, and the working conditions of the operators are very bad, which also affects the quality of the product to a certain extent. In order to improve the quality of the product and reduce the labor intensity of the workers, a set of dyeing automation controllers is designed, which is mainly used to realize the single-machine control of the dyeing process, complete the setting and display of the step-up temperature dyeing process, automatic control and other functions, and reserve an interface for access to the fieldbus control system.
1 Scheme Design
During the dyeing process, the temperature detection of the inner and outer cylinders of the dyeing tank uses a PT100 temperature sensor; the step-up temperature process uses a PID algorithm to control the solenoid valve to control the temperature of the dye liquid; in the insulation stage, a solid-state relay is used to control the forward and reverse rotation of the reel DC motor to achieve uniform dyeing of the fabric.
The dyeing automation controller uses the MC9S12XDP512 microcontroller as the control core, and its system block diagram is shown in Figure 2. The system is divided into three parts: human-machine interaction unit, field control unit and CAN bus unit. Among them, the human-machine interaction unit consists of digital display, LED display and keyboard input, which is used for setting and displaying the dyeing process and displaying and alarming the operating status. The field control unit adopts a parallel bus, expands a 12-bit high-precision A/D converter, samples the temperature signal detected by PT100 and conditioned, and uses PID algorithm to control the temperature of the dye solution; at the same time, it completes the forward and reverse rotation of the fabric to realize the automatic control of the dyeing process. The CAN bus unit adopts the MC9S12XDP512 built-in CAN module to realize the architecture of the field bus control system.

2 Hardware Design
2.1 MC9S12XDP512
MC9S12XDP512 is a new generation 16-bit microcontroller produced by Freescale. It is based on the enhanced HCS12 core and integrates the peripheral coprocessor XGATE[2].
XGATE is a programmable RISC core independent of the HCS12X main CPU. It can be used as an efficient DMA controller to autonomously perform high-speed data transfer between peripherals and RAM and perform flexible data processing during data transfer.
The XGATE reduced instruction set core has 8 16-bit general registers R0~R7, 1 program counter PC, and 1 4-bit condition code register CCR. XGATE has a total of 72 independent instructions, and the instruction clock can reach up to 100 MHz, which is twice the bus speed of the HCS12X main CPU; it can access 64 KB of on-chip space, including 2 KB of on-chip peripheral registers, 30 KB of on-chip FLASH and a maximum of 32 KB of on-chip RAM.
2.2 XGATE Programming
XGATE code execution is driven by events (interrupts). Figure 3 shows a typical interrupt processing process of the S12X system microcontroller. The interrupt configuration register INT_CFGDATAx determines the interrupt processing core and interrupt priority. If the RQST position is 1, the XGTE coprocessor is selected to handle the current interrupt; otherwise, the HCS12X main processor is selected. When the XGATE interrupt service routine is processed, it notifies HCS12X and submits the processing results to HCS12X. In this way, HCS12X only needs to focus on the upper-level control algorithm, while the hardware operations closely related to the bottom layer are processed by XGATE, which greatly improves system performance [3].

In the textile industry, dyeing is an important production link for textile coloring. Fabric dyeing requires that a certain heating rate or cooling rate must be followed during different heating and cooling processes. In addition, different dyes and textiles require different temperature change curves for dye liquor [1]. Figure 1 shows a typical step-by-step heating process in actual production. The process is divided into three sections: the first section has a holding temperature of 80 °C and the number of forward and reverse rotations (passes) required during the holding period is 1; the second section has a holding temperature of 90 °C and 1 pass; the third section has a holding temperature of 135 °C and 2 passes.

For a long time, the dyeing process has been completed by general temperature controllers in combination with manual operation. This manual control dyeing method based on general temperature controllers is difficult to ensure the strict temperature increase and decrease rate required by the process, and different workers will also have differences when operating the same process requirements, thus affecting the quality and output of the product. At the same time, the temperature and humidity in the dyeing workshop are high, and the working conditions of the operators are very bad, which also affects the quality of the product to a certain extent. In order to improve the quality of the product and reduce the labor intensity of the workers, a set of dyeing automation controllers is designed, which is mainly used to realize the single-machine control of the dyeing process, complete the setting and display of the step-up temperature dyeing process, automatic control and other functions, and reserve an interface for access to the fieldbus control system.
1 Scheme Design
During the dyeing process, the temperature detection of the inner and outer cylinders of the dyeing tank uses a PT100 temperature sensor; the step-up temperature process uses a PID algorithm to control the solenoid valve to control the temperature of the dye liquid; in the insulation stage, a solid-state relay is used to control the forward and reverse rotation of the reel DC motor to achieve uniform dyeing of the fabric.
The dyeing automation controller uses the MC9S12XDP512 microcontroller as the control core, and its system block diagram is shown in Figure 2. The system is divided into three parts: human-machine interaction unit, field control unit and CAN bus unit. Among them, the human-machine interaction unit consists of digital display, LED display and keyboard input, which is used for setting and displaying the dyeing process and displaying and alarming the operating status. The field control unit adopts a parallel bus, expands a 12-bit high-precision A/D converter, samples the temperature signal detected by PT100 and conditioned, and uses PID algorithm to control the temperature of the dye solution; at the same time, it completes the forward and reverse rotation of the fabric to realize the automatic control of the dyeing process. The CAN bus unit adopts the MC9S12XDP512 built-in CAN module to realize the architecture of the field bus control system.

2 Hardware Design
2.1 MC9S12XDP512
MC9S12XDP512 is a new generation 16-bit microcontroller produced by Freescale. It is based on the enhanced HCS12 core and integrates the peripheral coprocessor XGATE[2].
XGATE is a programmable RISC core independent of the HCS12X main CPU. It can be used as an efficient DMA controller to autonomously perform high-speed data transfer between peripherals and RAM and perform flexible data processing during data transfer.
The XGATE reduced instruction set core has 8 16-bit general registers R0~R7, 1 program counter PC, and 1 4-bit condition code register CCR. XGATE has a total of 72 independent instructions, and the instruction clock can reach up to 100 MHz, which is twice the bus speed of the HCS12X main CPU; it can access 64 KB of on-chip space, including 2 KB of on-chip peripheral registers, 30 KB of on-chip FLASH and a maximum of 32 KB of on-chip RAM.
2.2 XGATE Programming
XGATE code execution is driven by events (interrupts). Figure 3 shows a typical interrupt processing process of the S12X system microcontroller. The interrupt configuration register INT_CFGDATAx determines the interrupt processing core and interrupt priority. If the RQST position is 1, the XGTE coprocessor is selected to handle the current interrupt; otherwise, the HCS12X main processor is selected. When the XGATE interrupt service routine is processed, it notifies HCS12X and submits the processing results to HCS12X. In this way, HCS12X only needs to focus on the upper-level control algorithm, while the hardware operations closely related to the bottom layer are processed by XGATE, which greatly improves system performance [3].