MCBSTR9: SSP1 Interface Does Not Work

Information in this article applies to:

• MCBSTR9 Evaluation Boards Version 2 and 3

QUESTION

I want to use the SSP1 interface on the Keil MCBSTR9 board, but it does not work. I never see the clock signal on Pin P3.4 (SSP1 master or slave clock). Are there any known problems with this interface on this board?

ANSWER

The pin P3.4 is also used as an interrupt input from the external Ethernet-PHY (STE100P). Unfortunately, this device drives this pin low. Since there is no way to disable this PHY interrupt output by software, the connection from pin 61 of the STE100P to Port3.4 of the STR912 microcontroller needs to be cut in order to use the SSP1 interface.

Download the picture (in the Attached Files below) of the PCB layout to see the wiring on all layers of the board. You may cut the circuit from the left pad of R46 (highlighted in red) that goes up to the via. The connection from the port connector to the microcontroller is not affected and can still be used.

This issue was fixed in board version 4 and higher.

MORE INFORMATION

• Refer to Schematics in the MCBSTR9 User's Guide.

ATTACHED FILES

Request the files attached to this knowledgebase article.

Last Reviewed: Wednesday, January 13, 2021