L6480H, some of our prototypes are not starting because the driver bridges are in high impedance mode and will not go out of the high impedance mode when we send any motion command to the L6480H.

JVilh.1868 · ‎2019-10-14

We are using L6480H, some of our prototypes are not starting because the driver bridges are in high impedance mode and will not go out of the high impedance mode when we send any motion command to the L6480H. We have not Over current event.

Working boards and not working boards have all the same register status when we send motion command to the L6480H.

This happens on 10-20% of the boards.

From Data sheet "Any motion command causes the device to exit from High Z state (HardStop and SoftStop included)

Best regards

Jon

Kurtnelle · ‎2019-10-14

A few things to try. First check that the standby pin is asserted. It should be connected to vcc. Check the status of the flag pin, on first power up it should be low (for undervoltage lockout) do get status to clear it. Check that the chip is responding to serial data. Send more bytes than you have drivers to ensure that the data your sending is being output by the chip ( on the spi bus). Last check that the motor you are using isn't causing an immediate over current condition. As soon as you give a movement command, it the driver may be sending a dead short or a motor with too low of an impedence. i had to use power resistors in series with the phase to be able to test certain motors.

JVilh.1868 · ‎2019-10-16

On some boards is the ULV0 bit = 0 in the STATUS register. Sending "get status" to L6480H will set the ULV0 bit = 1 on some boards, on other boards not. But by sending the "get status" to L6480H the UVLO_ADC bit in the STATUS register will always be set to 1.

On few boards the ULV0 will go to 0 immediately after sending RUN command to L6480H and then the motor will not run. Happens with the stepper motor connected and not connected.

Kurtnelle · ‎2019-10-16

What voltage are you driving the board with? Put a scope on the power nets and see if the voltages drop below 8v when you do a move command.