diff --git a/firmware/common/operacake.c b/firmware/common/operacake.c
index 50bc9339..02d16851 100644
--- a/firmware/common/operacake.c
+++ b/firmware/common/operacake.c
@@ -22,36 +22,39 @@
 #include "operacake.h"
 #include "hackrf_core.h"
 
-#define OPERACAKE_PIN_OE      (1<<7)
-#define OPERACAKE_PIN_U2CTRL1 (1<<6)
-#define OPERACAKE_PIN_U2CTRL0 (1<<5)
-#define OPERACAKE_PIN_U3CTRL1 (1<<4)
-#define OPERACAKE_PIN_U3CTRL0 (1<<3)
-#define OPERACAKE_PIN_U1CTRL  (1<<2)
-#define OPERACAKE_PIN_LEDEN2  (1<<1)
-#define OPERACAKE_PIN_LEDEN   (1<<0)
+#define OPERACAKE_PIN_OE(x)      (x<<7)
+#define OPERACAKE_PIN_U2CTRL1(x) (x<<6)
+#define OPERACAKE_PIN_U2CTRL0(x) (x<<5)
+#define OPERACAKE_PIN_U3CTRL1(x) (x<<4)
+#define OPERACAKE_PIN_U3CTRL0(x) (x<<3)
+#define OPERACAKE_PIN_U1CTRL(x)  (x<<2)
+#define OPERACAKE_PIN_LEDEN2(x)  (x<<1)
+#define OPERACAKE_PIN_LEDEN(x)   (x<<0)
 
-#define OPERACAKE_PA1 (0)
-#define OPERACAKE_PA2 (OPERACAKE_PIN_U2CTRL0)
-#define OPERACAKE_PA3 (OPERACAKE_PIN_U2CTRL1)
-#define OPERACAKE_PA4 (OPERACAKE_PIN_U2CTRL0 | OPERACAKE_PIN_U2CTRL1)
+#define OPERACAKE_PORT_A1 (OPERACAKE_PIN_U2CTRL0(0) | OPERACAKE_PIN_U2CTRL1(0))
+#define OPERACAKE_PORT_A2 (OPERACAKE_PIN_U2CTRL0(1) | OPERACAKE_PIN_U2CTRL1(0))
+#define OPERACAKE_PORT_A3 (OPERACAKE_PIN_U2CTRL0(0) | OPERACAKE_PIN_U2CTRL1(1))
+#define OPERACAKE_PORT_A4 (OPERACAKE_PIN_U2CTRL0(1) | OPERACAKE_PIN_U2CTRL1(1))
 
-#define OPERACAKE_PB1 (0)
-#define OPERACAKE_PB2 (OPERACAKE_PIN_U3CTRL0)
-#define OPERACAKE_PB3 (OPERACAKE_PIN_U3CTRL1)
-#define OPERACAKE_PB4 (OPERACAKE_PIN_U3CTRL0 | OPERACAKE_PIN_U3CTRL1)
+#define OPERACAKE_PORT_B1 (OPERACAKE_PIN_U3CTRL0(0) | OPERACAKE_PIN_U3CTRL1(0))
+#define OPERACAKE_PORT_B2 (OPERACAKE_PIN_U3CTRL0(1) | OPERACAKE_PIN_U3CTRL1(0))
+#define OPERACAKE_PORT_B3 (OPERACAKE_PIN_U3CTRL0(0) | OPERACAKE_PIN_U3CTRL1(1))
+#define OPERACAKE_PORT_B4 (OPERACAKE_PIN_U3CTRL0(1) | OPERACAKE_PIN_U3CTRL1(1))
 
-#define OPERACAKE_CROSSOVER (0)
-#define OPERACAKE_EN_LEDS (OPERACAKE_PIN_LEDEN2)
+#define OPERACAKE_SAMESIDE  OPERACAKE_PIN_U1CTRL(1)
+#define OPERACAKE_CROSSOVER OPERACAKE_PIN_U1CTRL(0)
+#define OPERACAKE_EN_LEDS (OPERACAKE_PIN_LEDEN2(1) | OPERACAKE_PIN_LEDEN2(0))
+#define OPERACAKE_GPIO_EN OPERACAKE_PIN_OE(0)
+#define OPERACAKE_GPIO_DISABLE OPERACAKE_PIN_OE(1)
 
 #define OPERACAKE_REG_INPUT    0x00
 #define OPERACAKE_REG_OUTPUT   0x01
 #define OPERACAKE_REG_POLARITY 0x02
 #define OPERACAKE_REG_CONFIG   0x03
 
-#define OPERACAKE_DEFAULT_OUTPUT (OPERACAKE_PIN_OE | OPERACAKE_PIN_U1CTRL | \
-								  OPERACAKE_PA1 | OPERACAKE_PB1 | \
-								  OPERACAKE_EN_LEDS)
+#define OPERACAKE_DEFAULT_OUTPUT (OPERACAKE_GPIO_DISABLE | OPERACAKE_SAMESIDE \
+								  | OPERACAKE_PORT_A1 | OPERACAKE_PORT_B1 \
+								  | OPERACAKE_EN_LEDS)
 #define OPERACAKE_CONFIG_ALL_OUTPUT (0x00)
 
 typedef struct {
@@ -79,16 +82,58 @@ uint8_t operacake_init(void) {
 	return 0;
 }
 
-uint8_t operacake_set_ports(uint8_t PA, uint8_t PB) {
-	return PA | PB;
+uint8_t port_to_pins(uint8_t port) {
+	switch(port) {
+		case OPERACAKE_PA1:
+			return OPERACAKE_PORT_A1;
+		case OPERACAKE_PA2:
+			return OPERACAKE_PORT_A2;
+		case OPERACAKE_PA3:
+			return OPERACAKE_PORT_A3;
+		case OPERACAKE_PA4:
+			return OPERACAKE_PORT_A4;
+
+		case OPERACAKE_PB1:
+			return OPERACAKE_PORT_B1;
+		case OPERACAKE_PB2:
+			return OPERACAKE_PORT_B2;
+		case OPERACAKE_PB3:
+			return OPERACAKE_PORT_B3;
+		case OPERACAKE_PB4:
+			return OPERACAKE_PORT_B4;
+	}
+	return 0xFF;
 }
 
-/* read single register */
-uint8_t operacake_read_single(operacake_driver_t* drv, uint8_t reg) {
-	const uint8_t data_tx[] = { reg };
-	uint8_t data_rx[] = { 0x00 };
-	i2c_bus_transfer(drv->bus, drv->i2c_address, data_tx, 1, data_rx, 1);
-	return data_rx[0];
+uint8_t operacake_set_ports(uint8_t PA, uint8_t PB) {
+	uint8_t side, pa, pb;
+	uint8_t output_data[2];
+	/* Start with some error checking,
+	 * which should have been done either
+	 * on the host or elsewhere in firmware
+	 */
+	if((PA > OPERACAKE_PB4) || (PB > OPERACAKE_PB4)) {
+		return 1;
+	}
+	/* Check which side PA and PB are on */
+	if(((PA <= OPERACAKE_PA4) && (PB <= OPERACAKE_PA4))
+	    || ((PA > OPERACAKE_PA4) && (PB > OPERACAKE_PA4))) {
+		return 1;
+	}
+	
+	if(PA > OPERACAKE_PA4)
+		side = OPERACAKE_CROSSOVER;
+	else
+		side = OPERACAKE_SAMESIDE;
+
+		pa = port_to_pins(PA);
+		pb = port_to_pins(PB);
+		
+	output_data[0] = OPERACAKE_REG_OUTPUT;
+	output_data[1] = (OPERACAKE_GPIO_DISABLE | side
+					| pa | pb | OPERACAKE_EN_LEDS);
+	operacake_write(&operacake_driver, output_data, 2);
+	return 0;
 }
 
 /* Write to one of the PCA9557 registers */
diff --git a/firmware/common/operacake.h b/firmware/common/operacake.h
index 33c35a4f..20a9a998 100644
--- a/firmware/common/operacake.h
+++ b/firmware/common/operacake.h
@@ -30,6 +30,16 @@ extern "C"
 #include <stdint.h>
 #include "i2c_bus.h"
 
+#define OPERACAKE_PA1 0
+#define OPERACAKE_PA2 1
+#define OPERACAKE_PA3 2
+#define OPERACAKE_PA4 3
+
+#define OPERACAKE_PB1 4
+#define OPERACAKE_PB2 5
+#define OPERACAKE_PB3 6
+#define OPERACAKE_PB4 7
+
 uint8_t operacake_init(void);
 uint8_t operacake_set_ports(uint8_t PA, uint8_t PB);
 
diff --git a/firmware/hackrf_usb/usb_api_operacake.c b/firmware/hackrf_usb/usb_api_operacake.c
index 7ac4da81..c93ec494 100644
--- a/firmware/hackrf_usb/usb_api_operacake.c
+++ b/firmware/hackrf_usb/usb_api_operacake.c
@@ -22,15 +22,13 @@
 #include "usb_api_operacake.h"
 #include "usb_queue.h"
 
-#include <stddef.h>
-#include <hackrf_core.h>
 #include <operacake.h>
 
 usb_request_status_t usb_vendor_request_operacake_set_ports(
 		usb_endpoint_t* const endpoint, const usb_transfer_stage_t stage)
 {
 	if (stage == USB_TRANSFER_STAGE_SETUP) {
-		/* TODO: implement something */
+		operacake_set_ports(endpoint->setup.index, endpoint->setup.value);
 		usb_transfer_schedule_ack(endpoint->in);
 	}
 	return USB_REQUEST_STATUS_OK;