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- MASTER THE BOARDS STEP 3 NEW EDITION DRIVERS
- MASTER THE BOARDS STEP 3 NEW EDITION DRIVER
- MASTER THE BOARDS STEP 3 NEW EDITION MANUAL
- MASTER THE BOARDS STEP 3 NEW EDITION SERIES
If the user turns on TB_A switch then the first motor driver goes into the parallel mode and its directional pins are shorted, where GPIO connections are IN1 = IN3 = 25 and IN2 = IN4 = 26.
MASTER THE BOARDS STEP 3 NEW EDITION MANUAL
Note: The directional pin shorting is done by a manual DPDT switch.Thus, two high rated motors can be controlled using ESP32. two channels, giving a current capacity of 2.4A. In this mode, the channel's directional pins and output pins are shorted only one motor is connected to a motor driver i.e.The parallel mode is a special feature, used for high-rated motors, requiring more than the 1.2A current limit.So in normal mode, 4 motors can be connected to the board, with a per channel/motor current capacity of 1.2A.E.g.: If pin 32 is HIGH(IN1 = HIHG) and pin 33 is low(IN2 = LOW) then motor 1 moves in the forward direction.Therefore, using two motor driver one can control 4 motors using 8 GPIO's of ESP32. As discussed earlier, the new design has two motor drivers.This motor driver is characterized by its operation in two modes - Normal mode and Parallel mode:
MASTER THE BOARDS STEP 3 NEW EDITION DRIVERS
The new edition has 2x TB6612FNG motor drivers which allow a maximum of 4 motors to be controlled. So, for higher current capacity motors, two TB6612FNG are given on the board, which can be used in parallel mode to double the current capacity to 2.4A. The only drawback of TB6612FNG is the less continuous current which is equal to 1.2A.As you can see the efficiency of TB6612FNG can reach up to 91-95% which is significantly higher than the 40-70% efficiency of L298N. The detailed comparison is shown below.L298N is a BJT-based H-bridge motor driver but it is less efficient as compared to the new MOS-based TB6612FNG.So, the new edition uses the P-MOSFET instead of a diode, which is more efficient and can handle more current.
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( As the current rating of diode increases, its size also increases.) Dut to the usage of high-rated motors, it was difficult to manage the diode size and the current rating.
MASTER THE BOARDS STEP 3 NEW EDITION SERIES
Diodes in series to the power line are inefficient as compare to a P-MOSFET.Reverse voltage protection: Diodes to P-MOSFET.( AMS1117 is used in the ESP32-DevKitC V4 module) The previous edition used the LD33 IC to step down from 5V to 3.3V several discussions resulted in the shift to more compact, reliable AMS1117(SOT-23) linear voltage regulator.The LM2596 can provide current up to 3A, so the MARIO workshop manipulator can now be run using onboard regulator. The efficiency of LM2596 is up to 92% which is significantly better than 7805.The greater efficiency, output current and reliability of LM2596 were the reasons for this change.7805 (5V linear regulator) to LM2596 Buck Convertor.Now that we covered basics of development boards, let us talk about the changes made in the new design. Similarly, there was a switch for the ESP32 MCU. The SRA Board 2019 had a power switch for the motor driver, using which power supply to the motor driver can be toggled.The previous edition had a pair of programmable switches and programmable LEDs each.Every development board should have some programmable switches and LEDs for testing, control and debugging purposes.For the overcurrent protection of MCU and motor driver circuit, fuses of 300mA and 3A were used respectively.The SRA Board 2019 used diodes for reverse voltage protection in the power-line.Protection against Reverse Voltage and Over Current.The SRA Board 2019 had two sensor ports - one for a LSA (line sensor array) and the second for the MPU6050.According to the external sensor types, usually development boards have onboard sensor ports where the sensors can be connected easily using FRC connector.The SRA Board 2019 used the L298N IC for motor-control, which is a BJT-based H-Bridge motor driver.
So, an external motor driver circuitry is required to control motors according to the MCU input.
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For more details of the SRA board 2019, checkout this link.