Ejemplo de MAX485 sin Microcontrolador

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Set R11's Resistance to "680Ω"

Set R12's Resistance to "680Ω"

93 days

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Autopilot
Work done
  • Updated project description to include USB–RS-485 (RTS controlled) block
  • Added U5 as the MAX485 transceiver
Tasks not yet done
  • Add termination resistor: 120 Ω Resistor
  • Add two bias resistors: 680 Ω Resistor ×2
  • Add TVS protection: Bidirectional TVS Diode
  • Wire IC1 TXD→MAX485 DI, RO→IC1 RXD, tie RTS→DE/RE
  • Expose bus via new portals: RS485_A, RS485_B
  • Connect MAX485 VCC and GND to +5 V and GND
  • Label block “USB–RS-485 (RTS controlled)”
  • Run ERC/DRC checks
Cannot do
  • Adding a MAX3485 transceiver (step 2.1 requires MCU support)
Success criteria
  • Partially met: MAX485 block added. Remaining success criteria (resistors, termination, diode, wiring, portals, power, checks) still to implement.
Next step Add the supporting components (#3): place and configure the 120 Ω termination resistor, two 680 Ω bias resistors, and the TVS diode across A/B.
93 days

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please explain what IC3 does.
lcruz2214

lcruz2214

@copilot please explain what IC3 does.
1y

copilot

The component IC3\text{IC3} is a MAX3485 transceiver from Maxim Integrated. It is used for RS-485 and RS-422 communication, which are standards for electrical characteristics of digital signaling circuits used in serial communications systems.
Key Features:
  • Half-Duplex Communication: The MAX3485 is capable of half-duplex communication, which means it can either send or receive data at a given time, but not both simultaneously.
  • Differential Signaling: RS-485 uses differential signaling, which makes it very resilient to noise in electrically noisy environments, allowing reliable data communication over long distances.
  • Low Power: It typically has a low current consumption, suitable for battery-powered and other power-sensitive applications.
Pin Functions in Connection:
  • RO (Pin 1): Receiver Output. This pin is used to output the data received from the RS-485 bus.
  • ~RE (Pin 2): Receiver Enable. This active-low pin enables the receiver. When it is low, the receiver is enabled.
  • DE (Pin 3): Driver Enable. When this pin is high, the driver is enabled, allowing transmitted data to be sent to the RS-485 bus.
  • DI (Pin 4): Driver Input. This pin is used to send data to the RS-485 bus when the driver is enabled.
  • GND (Pin 5): Ground connection.
  • A and B (Pins 6 and 7): These pins are the differential data transmission pins for the RS-485 bus.
  • VCC (Pin 8): Supply voltage, typically 3.3V or 5V.
Application in Your Project:
In your ESP32 RS485 Modbus Controller project, the MAX3485 allows the ESP32 to communicate with other Modbus devices over an RS-485 bus, handling the electrical signaling and protocol level requirements for effective communication over such a bus.
1y
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create a detailed step by step plan table for IC3 to verify its functionality.
dgamarra

dgamarra

@copilot create a detailed step by step plan table for IC3 to verify its functionality.
1y

copilot

To verify the functionality of the MAX3485CSA+, an RS-485 transceiver, we'll create a step-by-step plan to test its key features. This involves checking power supply, communication lines, and driver/receiver functionality. Below is a detailed plan table for performing these tests:

Table

StepActionExpected OutcomeNotes
1Power Supply CheckMeasure voltage at VCC pinVoltage should be within operational range 4.5V to 5.5V
2Ground ConnectionCheck GND pin connectionShould be properly grounded
3Idle StateObserve voltage levels at A and B lines with no inputLines should be in high impedance state
4Driver Enable TestSet DE high and ~RE high (connected to a pull-down resistor or ensure it stays high)Voltages should appear on A and B lines
5Driver Data TestInput a signal on DI pin and monitor A and B linesA should follow DI, B should be inverted
6Receiver Enable TestSet ~RE low (connect DE low or ensure it stays low)RO should reflect A-B differential
7Receiver Data TestApply differential signals to A and B lines and monitor RORO should output logic level equivalent to A-B
8Loopback TestConnect DI to RO and verify loopback operationRO should replicate DI signal
9Fault Condition TestShort A and B to GND; observe RO and output on A/BRO should remain consistent, A and B should handle short
10Termination Resistor CheckApply termination resistors and measure line reflectionsSignal reflections should be minimized
11Data Rate TestingSend data at various baud ratesData should be consistently received without errors
Additional Notes:
  • Make sure all testing instruments are properly calibrated.
  • Use a known good sample or reference circuit for comparison.
  • Ensure that static-sensitive devices are properly handled with ESD precautions.
  • Document and analyze all observations for further debugging and validation.
This plan provides a comprehensive approach to verifying the functionality of your MAX3485CSA+ in a systematic manner. If you have access to an oscilloscope and function generator, these tests can be made more precise. Let me know if you need more detailed guidance on any particular step!
1y
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4
please explain what USB1 does.
juanmiguel003

juanmiguel003

@copilot please explain what USB1 does.
1y

copilot

The component USB1 in your project is a USB Type-C connector, with the specific part number TYPE-C-31-M-12. This connector is used for providing power and data interfaces to your ESP32 RS485 (Modbus) Controller module. Here's a general breakdown of its functionality based on the pins described:
  • VBUS (Pins 15, 16): Supplies power to the circuit. In this design, it's connected to a voltage regulator to provide stable power.
  • GND (Pins 7, 8): Ground connections ensure a common return path for electrical current.
  • DP1, DN1, DP2, DN2 (Pins 2, 3, 12, 13): These pins are for data communication. They are typically used for differential signaling (D+ and D-).
  • CC1, CC2 (Pins 1, 11): Configuration channel pins are used for USB Type-C cable orientation detection and power delivery negotiations.
  • SBU1, SBU2 (Pins 4, 14): Sideband use pins, typically utilized in alternate modes.
  • SHIELD (Pins 5, 6, 9, 10): Provide additional grounding and shielding for the connector.
Overall, USB1 serves as the interface for both power and data connectivity, allowing the device to be powered and communicate with external devices through the USB protocol. If you have any specific questions on how to connect it or use it in your design, feel free to ask!
1y
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6
please explain what USB1 does.
juanmiguel003

juanmiguel003

@copilot please explain what USB1 does.
1y

copilot

The component USB1 is a USB Type-C connector, model TYPE-C-31-M-12 by Korean Hroparts Elec. In this design, it serves as the interface for power and data connections:
  • Power Connection: The USB1 connector provides the +5V power supply, which can be used to power the board and its components. The VBUS pins (Pins 15 and 16) handle the voltage input.
  • Data Connection: It features two differential data lines, DP1 (Pin 2) and DN1 (Pin 3) for one side of the connector, and DP2 (Pin 12) and DN2 (Pin 13) for the other, intended for USB data communication. These are connected to the CH340C USB to serial converter chip for serial communication.
  • Ground and Shield: The GND pins (Pins 7 and 8) and SHIELD pins (Pins 5, 6, 9, and 10) are used for grounding and shielding purposes.
This setup allows for both charging the device and facilitating data exchange with connected devices, like a host computer.
1y
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7
create a detailed step by step plan table for IC3 to verify its functionality.
dgamarra

dgamarra

@copilot create a detailed step by step plan table for IC3 to verify its functionality.
1y

copilot

To verify the functionality of the MAX3485CSA+, which is an RS-485 transceiver, you can follow the steps in the table below. Each step outlines a particular test to ensure the transceiver is working as expected.

Table

StepDescriptionProcedureExpected Outcome
1Power Supply VerificationPower up the IC with appropriate supply voltage (VCC typically 3.3V or 5V). Measure the voltage at the VCC pin to ensure it is within the specified range.VCC pin should measure near 3.3V or 5V, depending on your supply.
2Idle Condition CheckWith both ~RE and DE pins low, measure the voltages at A and B pins.Both A and B should be in the high impedance state.
3Receiver Functionality TestApply a differential signal across A and B. Monitor RO pin for the corresponding logic level.RO should reflect the logic level of the A and B differential (high when the differential is positive; low when it is negative)(\text{high when the differential is positive; low when it is negative}).
4Driver Functionality TestDrive the DI pin with a logic high. Set DE high to enable the driver. Measure the differential output between A and B. Repeat with DI as logic low.A should be significantly higher than B when DI is high and vice versa.
5~RE & DE Control TestTest the ~RE and DE pins by varying their states and observing the behavior of RO and the A/B lines.DE high sets the driver active, ~RE low sets the receiver active.
6Short-Circuit and Overcurrent ProtectionConnect A and B to GND and apply a logic signal to DI with DE set high.There should be no significant increase in supply current, indicating the overcurrent protection is functional.
7Propagation Delay TestMeasure the time from a change in DI to a corresponding change in the A/B lines for drivers and vice versa for receivers.Propagation delay should match the datasheet specifications, generally within tens of nanoseconds.
Additional Notes:
  • Ensure all test setups are static-safe to prevent ESD damage to the IC.
  • Use a clean and stable power supply for all tests to avoid introducing noise.
  • Consider examining signal integrity with an oscilloscope to verify proper signal levels and lack of undue ringing or distortion.
If needed, perform these tests in a lab environment equipped with proper tools such as an oscilloscope, logic analyzer, and a reliable power supply to ensure accuracy and safety during the testing process. If any step yields unexpected results, trace connections, review the component datasheet, and check the conditions for further troubleshooting.
1y
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3
please explain what U1 does.
juanmiguel003

juanmiguel003

@copilot please explain what U1 does.
1y

copilot

The component U1U1 is the AMS1117-3.3, which is a voltage regulator that provides a stable output voltage of 3.3V. It is commonly used to power microcontrollers and other digital logic circuits that require a 3.3V supply.
Here is a brief explanation of its function and connections in your circuit:
  • VIN (Pin 3): This is the input voltage pin, which should be connected to a voltage higher than 3.3V (such as 5V from a USB source).
  • VOUT (Pin 2 and TAB(VOUT) Pin 4): These are the output voltage pins, providing a constant 3.3V.
  • GND (Pin 1): This is the ground pin, which should be connected to the ground plane of the circuit.
In your project:
  • The input voltage (U1U1:VIN) is connected to the 5V supply.
  • The output voltage (U1U1:VOUT and TAB(VOUT)) is connected to the 3.3V power net to supply power to components like the ESP32−WROOM−32EESP32-WROOM-32E and other peripherals requiring 3.3V.
  • The ground pin (U1U1:GND) is connected to the common ground.
This voltage regulator ensures that your digital components receive a stable 3.3V, providing reliable operation across varying input voltages.
1y
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5
RS485_TX
RS485_EN
GPIO34
RS485_B
GPIO25
RS485_A
GPIO35
GPIO33
RS485_RX
GPIO26
GPIO32
ESP_IO0
GPIO27
+3V3
+5V
R6
Resistance
10 Ω
R5
Resistance
10 Ω
+3V3
TERM
R7
Resistance
10 Ω
C10
Capacitance
0.1u F
IC3
C12
Capacitance
0.1u F
R8
Resistance
10k Ω
+3V3
BOOT
R9
Resistance
10k Ω
R10
Resistance
500 Ω
D3
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    Ground
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    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
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    Generic Resistor
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    Terminal
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    RMCF0805JT47K0
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ESP32 RS485 (Modbus) Controller Reference Design

ESP32 RS485 (Modbus) Controller Reference Design
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Last updated by vasy_skral
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vasy_skral

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