diff --git a/firmware/libboard/octsimtest/include/mcp23017.h b/firmware/libboard/octsimtest/include/mcp23017.h
index 962a1d5e..c0f4b131 100644
--- a/firmware/libboard/octsimtest/include/mcp23017.h
+++ b/firmware/libboard/octsimtest/include/mcp23017.h
@@ -18,7 +18,7 @@
 
 #define MCP23017_ADDRESS 0x20
 
-int mcp23017_init(uint8_t slave);
+int mcp23017_init(uint8_t slave, uint8_t iodira, uint8_t iodirb);
 int mcp23017_test(uint8_t slave);
 int mcp23017_toggle(uint8_t slave);
 //int mcp23017_write_byte(uint8_t slave, uint8_t addr, uint8_t byte);
diff --git a/firmware/libboard/octsimtest/source/board_octsimtest.c b/firmware/libboard/octsimtest/source/board_octsimtest.c
index 85d8aab4..404bef6e 100644
--- a/firmware/libboard/octsimtest/source/board_octsimtest.c
+++ b/firmware/libboard/octsimtest/source/board_octsimtest.c
@@ -17,6 +17,7 @@
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
  */
+#include <stdbool.h>
 #include "board.h"
 #include "simtrace.h"
 #include "utils.h"
@@ -27,6 +28,8 @@
 #include "mcp23017.h"
 #include "mux.h"
 
+static bool mcp2317_present = false;
+
 void board_exec_dbg_cmd(int ch)
 {
 	switch (ch) {
@@ -69,8 +72,9 @@ void board_main_top(void)
 
 	mux_init();
 	i2c_pin_init();
-	if (!mcp23017_init(MCP23017_ADDRESS))
-		printf("mcp23017 not found!\n\r");
+	/* PORT A: all outputs, Port B0 output, B1..B7 unused */
+	if (mcp23017_init(MCP23017_ADDRESS, 0x00, 0xfe) == 0)
+		mcp2317_present = true;
 	/* Initialize checking for card insert/remove events */
 	//card_present_init();
 #endif
diff --git a/firmware/libboard/octsimtest/source/mcp23017.c b/firmware/libboard/octsimtest/source/mcp23017.c
index 167bf340..a4d055f7 100644
--- a/firmware/libboard/octsimtest/source/mcp23017.c
+++ b/firmware/libboard/octsimtest/source/mcp23017.c
@@ -92,19 +92,25 @@ out_stop:
 		return 0;
 }
 
-int mcp23017_init(uint8_t slave)
+int mcp23017_init(uint8_t slave, uint8_t iodira, uint8_t iodirb)
 {
 	printf("mcp23017_init\n\r");
+
 	// all gpio input
-	if (mcp23017_write_byte(slave, MCP23017_IODIRA, 0xff))
-		return false;
+	if (mcp23017_write_byte(slave, MCP23017_IODIRA, iodira))
+		goto out_err;
 	// msb of portb output, rest input
-	if (mcp23017_write_byte(slave, MCP23017_IODIRB, 0x7f))
-		return false;
+	if (mcp23017_write_byte(slave, MCP23017_IODIRB, iodirb))
+		goto out_err;
 	if (mcp23017_write_byte(slave, MCP23017_IOCONA, 0x20)) //disable SEQOP (autoinc addressing)
-		return false;
+		goto out_err;
+
 	printf("mcp23017 found\n\r");
-	return true;
+	return 0;
+
+out_err:
+	printf("mcp23017 NOT found!\n\r");
+	return -1;
 }
 
 int mcp23017_test(uint8_t slave)