AN4068 datasheet(55/63 Pages) STMICROELECTRONICS

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AN4068

FAQs and troubleshooting

Doc ID 022923 Rev 2

55/63

11.2

Troubleshooting

Problem: the ST7580 reference design board doesn't work at all.

What to check:

Check that the AC mains supply cable is well connected.

Check the voltage on VCC, VDDIO, VCCA, VDD, VDD_PLL lines. All these

voltages must be present to turn the ST7580 on.

Verify if an 8-MHz clock is present on the XOUT pin (13) of the ST7580 device.

Problem: the ST7580 reference design board is not responding.

What to check:

Check if there is activity when trying to communicate via USB with the board.

Try disconnecting and reconnecting the USB cable; sometimes the USB driver

fails during COM port opening.

Try to reinstall the USB VCP driver for the STM32 on the PC.

Try to reprogram the STM32 with the VCP driver FW.

Problem: the ST7580 reference design board does not transmit.

What to check:

Check the bias voltage on the PA_OUT test point (TP1) with the oscilloscope

probe referred to VSS power ground. A DC voltage of VCC/2 must be measured.

Set the ST7580 in transmission via the ST7580 GUI. A modulated signal should

be detected by the oscilloscope probe, with amplitude equal to the TX_OUT

programmed level multiplied by the PA gain (see Section 7.1.1). If so, there is no

problem with the transmitter section of the ST7580.

Problem: the ST7580 reference design board transmits only for a short while; the

transmission is interrupted.

What to check:

Verify the internal temperature of the ST7580, available inside the management

information base (MIB) and accessible via the ST7580 GUI.

Check if there is short-circuit (i.e. capacitive) impedance on the mains at the

carrier frequency. It may lead to device overheating and PA thermal shutdown.

Problem: the ST7580 reference design board does not receive.

What to check:

Check if the transmitted signal reaches the ST7580 device by measuring the

RX_IN line voltage (TP5) with the oscilloscope probe referred to VSSA signal

ground.

Check that the GUI is setting the transmitter and the receiver to use the same tone

frequencies.

Problem: during a communication test, the ST7580 GUI shows high ‘bit error rate’

(BER).

Note:

This point refers to a half-duplex communication involving two ST7580 reference design

boards communicating with each other.

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