diff --git a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
index 110d9ffc8c..7df54650c9 100644
--- a/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
+++ b/libraries/AP_HAL_ChibiOS/hwdef/iomcu/hwdef.dat
@@ -97,8 +97,11 @@ define NO_DATAFLASH TRUE
 
 define DMA_RESERVE_SIZE 0
 
+# reduce memory usage in RCInput
+define SOFTSIG_MAX_SIGNAL_TRANSITIONS 256
+
 define IOMCU_FW TRUE
 define NO_FASTBOOT
 IOMCU_FW 1
 MAIN_STACK 0x200
-PROCESS_STACK 0x250
\ No newline at end of file
+PROCESS_STACK 0x250