diff --git a/contrib/ackbtn-stm32f103.c b/contrib/ackbtn-stm32f103.c
index 460940f..38a67ad 100644
--- a/contrib/ackbtn-stm32f103.c
+++ b/contrib/ackbtn-stm32f103.c
@@ -66,6 +66,15 @@ ackbtn_init (chopstx_intr_t *intr)
       pin_config |= PINCFG_EDGE_RISING;
       break;
 
+    case BOARD_ID_ST_DONGLE:
+      /* PA5 is connected to a switch */
+      afio_exticr_index = 0;
+      afio_exticr_extiX_pY = AFIO_EXTICR2_EXTI5_PA;
+      irq_num = EXTI9_5_IRQ;
+      pin_config = 0x0020; /* EXTI_PR_PR5 == EXTI_IMR_MR5 == EXTI_RTSR_TR5 */
+      pin_config |= PINCFG_EDGE_RISING;
+      break;
+
     case BOARD_ID_FST_01SZ:
     default:
       /* PA3 is connected to a hall sensor DRV5032FA */