diff --git a/klippy/extras/bus.py b/klippy/extras/bus.py
index ceeed732..c07ec826 100644
--- a/klippy/extras/bus.py
+++ b/klippy/extras/bus.py
@@ -160,6 +160,8 @@ class MCU_I2C:
         self.bus = bus
         self.i2c_address = addr
         self.oid = self.mcu.create_oid()
+        self.speed = speed
+        self.config_fmt_ticks = None
         mcu.add_config_cmd("config_i2c oid=%d" % (self.oid,))
         # Generate I2C bus config message
         if sw_pins is not None:
@@ -167,6 +169,10 @@ class MCU_I2C:
                 "i2c_set_software_bus oid=%d"
                 " scl_pin=%s sda_pin=%s rate=%d address=%d"
                 % (self.oid, sw_pins[0], sw_pins[1], speed, addr))
+            self.config_fmt_ticks = (
+                "i2c_set_sw_bus oid=%d"
+                " scl_pin=%s sda_pin=%s pulse_ticks=%%d address=%d"
+                % (self.oid, sw_pins[0], sw_pins[1], addr))
         else:
             self.config_fmt = (
                 "i2c_set_bus oid=%d i2c_bus=%%s rate=%d address=%d"
@@ -186,6 +192,12 @@ class MCU_I2C:
         if '%' in self.config_fmt:
             bus = resolve_bus_name(self.mcu, "i2c_bus", self.bus)
             self.config_fmt = self.config_fmt % (bus,)
+        if self.config_fmt_ticks:
+            if self.mcu.try_lookup_command("i2c_set_sw_bus oid=%c"
+                                           " scl_pin=%u sda_pin=%u"
+                                           " pulse_ticks=%u address=%u"):
+                pulse_ticks = self.mcu.seconds_to_clock(1./self.speed/2)
+                self.config_fmt = self.config_fmt_ticks % (pulse_ticks,)
         self.mcu.add_config_cmd(self.config_fmt)
         self.i2c_write_cmd = self.mcu.lookup_command(
             "i2c_write oid=%c data=%*s", cq=self.cmd_queue)
diff --git a/src/i2c_software.c b/src/i2c_software.c
index 805cef2d..01fce4c6 100644
--- a/src/i2c_software.c
+++ b/src/i2c_software.c
@@ -22,28 +22,21 @@ struct i2c_software {
 };
 
 void
-command_i2c_set_software_bus(uint32_t *args)
+command_i2c_set_sw_bus(uint32_t *args)
 {
     struct i2cdev_s *i2c = i2cdev_oid_lookup(args[0]);
     struct i2c_software *is = alloc_chunk(sizeof(*is));
-    uint32_t rate = args[3];
-    is->ticks = CONFIG_CLOCK_FREQ / (100000 * 2); // 100KHz
+    is->ticks = args[3];
     is->addr = (args[4] & 0x7f) << 1; // address format shifted
     is->scl_in = gpio_in_setup(args[1], 1);
     is->scl_out = gpio_out_setup(args[1], 1);
     is->sda_in = gpio_in_setup(args[2], 1);
     is->sda_out = gpio_out_setup(args[2], 1);
-    while (rate > 100000) {
-        rate = rate >> 1;
-        if (rate < 100000)
-            break;
-        is->ticks = is->ticks >> 1;
-    }
     i2cdev_set_software_bus(i2c, is);
 }
-DECL_COMMAND(command_i2c_set_software_bus,
-             "i2c_set_software_bus oid=%c scl_pin=%u sda_pin=%u"
-             " rate=%u address=%u");
+DECL_COMMAND(command_i2c_set_sw_bus,
+             "i2c_set_sw_bus oid=%c scl_pin=%u sda_pin=%u"
+             " pulse_ticks=%u address=%u");
 
 // The AVR micro-controllers require specialized timing
 #if CONFIG_MACH_AVR