diff --git a/artiq/firmware/libboard_misoc/io_expander.rs b/artiq/firmware/libboard_misoc/io_expander.rs
index edf2ce666..7009e0476 100644
--- a/artiq/firmware/libboard_misoc/io_expander.rs
+++ b/artiq/firmware/libboard_misoc/io_expander.rs
@@ -81,6 +81,32 @@ impl IoExpander {
         Ok(io_expander)
     }
 
+    #[cfg(soc_platform = "efc")]
+    pub fn new() -> Result<Self, &'static str> {
+        // TODO: Put Virtual User LEDs L0 L1 in gateware
+        const VIRTUAL_LED_MAPPING: [(u8, u8, u8); 2] = [(0, 0, 5), (1, 0, 6)];
+
+        let mut io_expander = IoExpander {
+            busno: 0,
+            port: 1,
+            address: 0x40,
+            virtual_led_mapping: &VIRTUAL_LED_MAPPING,
+            iodir: [0xff; 2],
+            out_current: [0; 2],
+            out_target: [0; 2],
+            registers: Registers {
+                iodira: 0x00,
+                iodirb: 0x01,
+                gpioa: 0x12,
+                gpiob: 0x13,
+            },
+        };
+        if !io_expander.check_ack()? {
+            return Err("MCP23017 io expander not found.");
+        };
+        Ok(io_expander)
+    }
+
     #[cfg(soc_platform = "kasli")]
     fn select(&self) -> Result<(), &'static str> {
         let mask: u16 = 1 << self.port;
@@ -89,6 +115,13 @@ impl IoExpander {
         Ok(())
     }
 
+    #[cfg(soc_platform = "efc")]
+    fn select(&self) -> Result<(), &'static str> {
+        let mask: u16 = 1 << self.port;
+        i2c::switch_select(self.busno, 0x70, mask as u8)?;
+        Ok(())
+    }
+
     fn write(&self, addr: u8, value: u8) -> Result<(), &'static str> {
         i2c::start(self.busno)?;
         i2c::write(self.busno, self.address)?;
diff --git a/artiq/firmware/libboard_misoc/lib.rs b/artiq/firmware/libboard_misoc/lib.rs
index 3189ccfcd..7ba835dcf 100644
--- a/artiq/firmware/libboard_misoc/lib.rs
+++ b/artiq/firmware/libboard_misoc/lib.rs
@@ -40,7 +40,7 @@ pub mod ethmac;
 pub mod i2c;
 #[cfg(soc_platform = "kasli")]
 pub mod i2c_eeprom;
-#[cfg(all(soc_platform = "kasli", hw_rev = "v2.0"))]
+#[cfg(any(all(soc_platform = "kasli", hw_rev = "v2.0"), soc_platform = "efc"))]
 pub mod io_expander;
 #[cfg(all(has_ethmac, feature = "smoltcp"))]
 pub mod net_settings;
diff --git a/artiq/firmware/satman/main.rs b/artiq/firmware/satman/main.rs
index 4e9f8fa33..cd101d28c 100644
--- a/artiq/firmware/satman/main.rs
+++ b/artiq/firmware/satman/main.rs
@@ -529,6 +529,19 @@ pub extern fn main() -> i32 {
 
     sysclk_setup();
 
+    #[cfg(soc_platform = "efc")]
+    {
+        let mut io_expander = board_misoc::io_expander::IoExpander::new().unwrap();
+        // Enable VADJ and P3V3_FMC
+        io_expander.set_oe(1, 1 << 0 | 1 << 1).unwrap();
+
+        io_expander.set(1, 0, true);
+        io_expander.set(1, 1, true);
+
+        io_expander.service().unwrap();
+    }
+
+    #[cfg(not(soc_platform = "efc"))]
     unsafe {
         csr::drtio_transceiver::txenable_write(0xffffffffu32 as _);
     }