diff --git a/README.md b/README.md
index b4da79a..5b79e52 100644
--- a/README.md
+++ b/README.md
@@ -124,8 +124,9 @@ A progressive series that introduces every peripheral one at a time.
 | [step6](tutorial/basics/step6/) | Analog joystick — a dot follows the stick on the display |
 | [step7](tutorial/basics/step7/) | Rotary encoder — turning cycles LED colors, push resets |
 | [step8](tutorial/basics/step8/) | Passive buzzer plays a note per button press |
-| [step9](tutorial/basics/step9/) | USB MIDI — badge sends notes C4 / E4 / G4 to any DAW |
-| [step10](tutorial/basics/step10/) | USB HID mouse — joystick moves the cursor, A/B click |
+| [step9](tutorial/basics/step9/) | Serial monitor — prints button, encoder, and joystick events over USB serial |
+| [step10](tutorial/basics/step10/) | USB MIDI — badge sends notes C4 / E4 / G4 to any DAW |
+| [step11](tutorial/basics/step11/) | USB HID mouse — joystick moves the cursor, A/B click |
 
 ---
 
diff --git a/TUTORIAL.md b/TUTORIAL.md
index 4880088..13ee469 100644
--- a/TUTORIAL.md
+++ b/TUTORIAL.md
@@ -409,7 +409,57 @@ Each button plays a different note while held.
 
 ---
 
-### step9 — USB MIDI
+### step9 — Serial monitor
+
+**Goal:** use `fmt.Println` and `fmt.Printf` to send human-readable events from the badge to your computer over USB serial.
+
+The `-monitor` flag tells TinyGo to open the serial port immediately after flashing, so you see the output without extra steps.
+
+```go
+// button press (falling-edge detection)
+a := btnA.Get()
+b := btnB.Get()
+c := btnC.Get() // rotary encoder push button
+if !a && prevA {
+    println("button A pressed")
+}
+if !b && prevB {
+    println("button B pressed")
+}
+if !c && prevC {
+    println("encoder button pressed")
+}
+
+// rotary encoder — print on every position change
+pos := enc.Position()
+if pos != prevPos {
+    println("encoder:", pos)
+    prevPos = pos
+}
+
+// joystick — print while outside the dead zone
+rawX := int(ax.Get()) - 32767
+rawY := int(ay.Get()) - 32767
+if rawX > deadzone || rawX < -deadzone || rawY > deadzone || rawY < -deadzone {
+    println("joystick:", "x=", rawX, "y=", rawY)
+}
+```
+
+```sh
+tinygo flash -target nicenano -monitor ./basics/step9
+```
+
+Move the joystick, turn the encoder knob, or press A, B, or the encoder button. Each event prints to your terminal in real time.
+
+**Key concepts**
+- `println` is a TinyGo built-in that writes directly to the USB serial port with no imports needed — prefer it over `fmt.Print*` in embedded code.
+- `-monitor` keeps the serial connection open after flashing — equivalent to running `tinygo monitor` right after.
+- Falling-edge detection (`!a && prevA`) prints once per press instead of flooding the terminal while the button is held.
+- A dead zone (`const deadzone = 5000`) suppresses joystick noise around the center resting position.
+
+---
+
+### step10 — USB MIDI
 
 **Goal:** make the badge appear as a MIDI instrument over USB.
 
@@ -426,7 +476,7 @@ midi.Midi.NoteOff(0, midichannel, notes[oldNote], 50)
 ```
 
 ```sh
-tinygo flash -target nicenano ./basics/step9
+tinygo flash -target nicenano ./basics/step10
 ```
 
 Open any online MIDI player (e.g. [muted.io/piano](https://muted.io/piano/)) or connect to a DAW. The three buttons play C4, E4, and G4 (a C major triad).
@@ -439,7 +489,7 @@ Open any online MIDI player (e.g. [muted.io/piano](https://muted.io/piano/)) or
 
 ---
 
-### step10 — USB HID mouse
+### step11 — USB HID mouse
 
 **Goal:** use the joystick as a mouse pointer and buttons as mouse clicks.
 
@@ -457,7 +507,7 @@ mouseDevice.Move(dx, dy)
 ```
 
 ```sh
-tinygo flash -target nicenano ./basics/step10
+tinygo flash -target nicenano ./basics/step11
 ```
 
 Connect the badge to a computer. The joystick moves the mouse cursor; button A is left click, button B is right click.
diff --git a/tutorial/basics/step10/main.go b/tutorial/basics/step10/main.go
index 50ddeef..64d873b 100644
--- a/tutorial/basics/step10/main.go
+++ b/tutorial/basics/step10/main.go
@@ -2,49 +2,46 @@ package main
 
 import (
 	"machine"
-	"machine/usb/hid/mouse"
+	"machine/usb/adc/midi"
 	"time"
 )
 
-const DEADZONE = 5000
-
 func main() {
 
-	// joystick analog axes
-	machine.InitADC()
-	ax := machine.ADC{Pin: machine.P0_02} // X axis
-	ay := machine.ADC{Pin: machine.P0_29} // Y axis
-	ax.Configure(machine.ADCConfig{})
-	ay.Configure(machine.ADCConfig{})
-
-	// A = left click, B = right click
+	// buttons: active LOW (internal pull-up)
 	btnA := machine.P1_06
 	btnB := machine.P1_04
+	btnRot := machine.P0_22 // rotary encoder push button
 	btnA.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 	btnB.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+	btnRot.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 
-	mouseDevice := mouse.Port()
+	// C major triad: C4, E4, G4
+	notes := []midi.Note{midi.C4, midi.E4, midi.G4}
+	midichannel := uint8(1)
 
+	note := -1
+	oldNote := -1
 	for {
-		// ADC center is ~32767; compute offset from center
-		rawX := int(ax.Get()) - 32767
-		rawY := int(ay.Get()) - 32767
-
-		var dx, dy int
-		if rawX > DEADZONE || rawX < -DEADZONE {
-			dx = rawX / 2048
-		}
-		if rawY > DEADZONE || rawY < -DEADZONE {
-			dy = rawY / 2048
-		}
-
-		mouseDevice.Move(dx, dy)
-
+		note = -1
 		if !btnA.Get() {
-			mouseDevice.Click(mouse.Left)
+			note = 0 // C4
 		}
 		if !btnB.Get() {
-			mouseDevice.Click(mouse.Right)
+			note = 1 // E4
+		}
+		if !btnRot.Get() {
+			note = 2 // G4
+		}
+
+		if note != oldNote {
+			if oldNote != -1 {
+				midi.Midi.NoteOff(0, midichannel, notes[oldNote], 50)
+			}
+			if note != -1 {
+				midi.Midi.NoteOn(0, midichannel, notes[note], 50)
+			}
+			oldNote = note
 		}
 
 		time.Sleep(100 * time.Millisecond)
diff --git a/tutorial/basics/step11/main.go b/tutorial/basics/step11/main.go
new file mode 100644
index 0000000..50ddeef
--- /dev/null
+++ b/tutorial/basics/step11/main.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"machine"
+	"machine/usb/hid/mouse"
+	"time"
+)
+
+const DEADZONE = 5000
+
+func main() {
+
+	// joystick analog axes
+	machine.InitADC()
+	ax := machine.ADC{Pin: machine.P0_02} // X axis
+	ay := machine.ADC{Pin: machine.P0_29} // Y axis
+	ax.Configure(machine.ADCConfig{})
+	ay.Configure(machine.ADCConfig{})
+
+	// A = left click, B = right click
+	btnA := machine.P1_06
+	btnB := machine.P1_04
+	btnA.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+	btnB.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+
+	mouseDevice := mouse.Port()
+
+	for {
+		// ADC center is ~32767; compute offset from center
+		rawX := int(ax.Get()) - 32767
+		rawY := int(ay.Get()) - 32767
+
+		var dx, dy int
+		if rawX > DEADZONE || rawX < -DEADZONE {
+			dx = rawX / 2048
+		}
+		if rawY > DEADZONE || rawY < -DEADZONE {
+			dy = rawY / 2048
+		}
+
+		mouseDevice.Move(dx, dy)
+
+		if !btnA.Get() {
+			mouseDevice.Click(mouse.Left)
+		}
+		if !btnB.Get() {
+			mouseDevice.Click(mouse.Right)
+		}
+
+		time.Sleep(100 * time.Millisecond)
+	}
+}
diff --git a/tutorial/basics/step6/main.go b/tutorial/basics/step6/main.go
index 5bfef78..67eb045 100644
--- a/tutorial/basics/step6/main.go
+++ b/tutorial/basics/step6/main.go
@@ -46,8 +46,9 @@ func main() {
 	var prevX, prevY int16
 	for {
 		// ADC returns 0-65535; map to display dimensions (240x135)
-		dotX := int16(uint32(ax.Get()) * 240 / 65535)
-		dotY := int16(uint32(ay.Get()) * 135 / 65535)
+		// -1 to avoid overflow
+		dotX := int16(uint32(ax.Get()-1) * 240 / 65535)
+		dotY := int16(uint32(-ay.Get()-1) * 135 / 65535)
 
 		// erase previous dot
 		tinydraw.FilledCircle(&display, prevX, prevY, 5, black)
diff --git a/tutorial/basics/step9/main.go b/tutorial/basics/step9/main.go
index 64d873b..5696df9 100644
--- a/tutorial/basics/step9/main.go
+++ b/tutorial/basics/step9/main.go
@@ -2,48 +2,64 @@ package main
 
 import (
 	"machine"
-	"machine/usb/adc/midi"
 	"time"
+
+	"tinygo.org/x/drivers/encoders"
 )
 
-func main() {
+const deadzone = 5000
 
-	// buttons: active LOW (internal pull-up)
+func main() {
 	btnA := machine.P1_06
 	btnB := machine.P1_04
-	btnRot := machine.P0_22 // rotary encoder push button
+	btnC := machine.P0_22 // rotary encoder push button
 	btnA.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 	btnB.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
-	btnRot.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
+	btnC.Configure(machine.PinConfig{Mode: machine.PinInputPullup})
 
-	// C major triad: C4, E4, G4
-	notes := []midi.Note{midi.C4, midi.E4, midi.G4}
-	midichannel := uint8(1)
+	enc := encoders.NewQuadratureViaInterrupt(machine.P1_00, machine.P0_24)
+	enc.Configure(encoders.QuadratureConfig{Precision: 4})
+
+	machine.InitADC()
+	ax := machine.ADC{Pin: machine.P0_02}
+	ay := machine.ADC{Pin: machine.P0_29}
+	ax.Configure(machine.ADCConfig{})
+	ay.Configure(machine.ADCConfig{})
+
+	prevA := true
+	prevB := true
+	prevC := true
+	prevPos := enc.Position()
 
-	note := -1
-	oldNote := -1
 	for {
-		note = -1
-		if !btnA.Get() {
-			note = 0 // C4
+		a := btnA.Get()
+		b := btnB.Get()
+		c := btnC.Get()
+		if !a && prevA {
+			println("button A pressed")
 		}
-		if !btnB.Get() {
-			note = 1 // E4
+		if !b && prevB {
+			println("button B pressed")
 		}
-		if !btnRot.Get() {
-			note = 2 // G4
+		if !c && prevC {
+			println("encoder button pressed")
+		}
+		prevA = a
+		prevB = b
+		prevC = c
+
+		pos := enc.Position()
+		if pos != prevPos {
+			println("encoder:", pos)
+			prevPos = pos
 		}
 
-		if note != oldNote {
-			if oldNote != -1 {
-				midi.Midi.NoteOff(0, midichannel, notes[oldNote], 50)
-			}
-			if note != -1 {
-				midi.Midi.NoteOn(0, midichannel, notes[note], 50)
-			}
-			oldNote = note
+		rawX := int(ax.Get()) - 32767
+		rawY := int(ay.Get()) - 32767
+		if rawX > deadzone || rawX < -deadzone || rawY > deadzone || rawY < -deadzone {
+			println("joystick:", "x=", rawX, "y=", rawY)
 		}
 
-		time.Sleep(100 * time.Millisecond)
+		time.Sleep(50 * time.Millisecond)
 	}
 }
diff --git a/tutorial/go.mod b/tutorial/go.mod
index f030f82..fd00589 100644
--- a/tutorial/go.mod
+++ b/tutorial/go.mod
@@ -1,3 +1,23 @@
 module code.madriguera.me/GoEducation/nicebadge/tutorial
 
 go 1.22.1
+
+require (
+	github.com/go-ole/go-ole v1.2.6 // indirect
+	github.com/godbus/dbus/v5 v5.1.0 // indirect
+	github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 // indirect
+	github.com/saltosystems/winrt-go v0.0.0-20240509164145-4f7860a3bd2b // indirect
+	github.com/sirupsen/logrus v1.9.3 // indirect
+	github.com/soypat/cyw43439 v0.0.0-20250505012923-830110c8f4af // indirect
+	github.com/soypat/seqs v0.0.0-20250124201400-0d65bc7c1710 // indirect
+	github.com/tinygo-org/cbgo v0.0.4 // indirect
+	github.com/tinygo-org/pio v0.3.0 // indirect
+	golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d // indirect
+	golang.org/x/sys v0.11.0 // indirect
+	tinygo.org/x/bluetooth v0.14.0 // indirect
+	tinygo.org/x/drivers v0.34.0 // indirect
+	tinygo.org/x/tinydraw v0.4.0 // indirect
+	tinygo.org/x/tinyfont v0.6.0 // indirect
+)
+
+replace tinygo.org/x/drivers => /home/conejo/go/src/tinygo.org/x/drivers
diff --git a/tutorial/go.sum b/tutorial/go.sum
index e69de29..85219da 100644
--- a/tutorial/go.sum
+++ b/tutorial/go.sum
@@ -0,0 +1,43 @@
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-ole/go-ole v1.2.6 h1:/Fpf6oFPoeFik9ty7siob0G6Ke8QvQEuVcuChpwXzpY=
+github.com/go-ole/go-ole v1.2.6/go.mod h1:pprOEPIfldk/42T2oK7lQ4v4JSDwmV0As9GaiUsvbm0=
+github.com/godbus/dbus/v5 v5.1.0 h1:4KLkAxT3aOY8Li4FRJe/KvhoNFFxo0m6fNuFUO8QJUk=
+github.com/godbus/dbus/v5 v5.1.0/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510 h1:El6M4kTTCOh6aBiKaUGG7oYTSPP8MxqL4YI3kZKwcP4=
+github.com/google/shlex v0.0.0-20191202100458-e7afc7fbc510/go.mod h1:pupxD2MaaD3pAXIBCelhxNneeOaAeabZDe5s4K6zSpQ=
+github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/saltosystems/winrt-go v0.0.0-20240509164145-4f7860a3bd2b h1:du3zG5fd8snsFN6RBoLA7fpaYV9ZQIsyH9snlk2Zvik=
+github.com/saltosystems/winrt-go v0.0.0-20240509164145-4f7860a3bd2b/go.mod h1:CIltaIm7qaANUIvzr0Vmz71lmQMAIbGJ7cvgzX7FMfA=
+github.com/sirupsen/logrus v1.5.0/go.mod h1:+F7Ogzej0PZc/94MaYx/nvG9jOFMD2osvC3s+Squfpo=
+github.com/sirupsen/logrus v1.9.3 h1:dueUQJ1C2q9oE3F7wvmSGAaVtTmUizReu6fjN8uqzbQ=
+github.com/sirupsen/logrus v1.9.3/go.mod h1:naHLuLoDiP4jHNo9R0sCBMtWGeIprob74mVsIT4qYEQ=
+github.com/soypat/cyw43439 v0.0.0-20250505012923-830110c8f4af h1:ZfFq94aH/BCSWWKd9RPUgdHOdgGKCnfl2VdvU9UksTA=
+github.com/soypat/cyw43439 v0.0.0-20250505012923-830110c8f4af/go.mod h1:MUaGO5m6X7xrkHrPDmnaxCEcuCCFN/0ZFh9oie+exbU=
+github.com/soypat/seqs v0.0.0-20250124201400-0d65bc7c1710 h1:Y9fBuiR/urFY/m76+SAZTxk2xAOS2n85f+H1CugajeA=
+github.com/soypat/seqs v0.0.0-20250124201400-0d65bc7c1710/go.mod h1:oCVCNGCHMKoBj97Zp9znLbQ1nHxpkmOY9X+UAGzOxc8=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+github.com/tinygo-org/cbgo v0.0.4 h1:3D76CRYbH03Rudi8sEgs/YO0x3JIMdyq8jlQtk/44fU=
+github.com/tinygo-org/cbgo v0.0.4/go.mod h1:7+HgWIHd4nbAz0ESjGlJ1/v9LDU1Ox8MGzP9mah/fLk=
+github.com/tinygo-org/pio v0.3.0 h1:opEnOtw58KGB4RJD3/n/Rd0/djYGX3DeJiXLI6y/yDI=
+github.com/tinygo-org/pio v0.3.0/go.mod h1:wf6c6lKZp+pQOzKKcpzchmRuhiMc27ABRuo7KVnaMFU=
+golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d h1:0olWaB5pg3+oychR51GUVCEsGkeCU/2JxjBgIo4f3M0=
+golang.org/x/exp v0.0.0-20241204233417-43b7b7cde48d/go.mod h1:qj5a5QZpwLU2NLQudwIN5koi3beDhSAlJwa67PuM98c=
+golang.org/x/sys v0.0.0-20190422165155-953cdadca894/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190916202348-b4ddaad3f8a3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.11.0 h1:eG7RXZHdqOJ1i+0lgLgCpSXAp6M3LYlAo6osgSi0xOM=
+golang.org/x/sys v0.11.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+tinygo.org/x/bluetooth v0.14.0 h1:rrUaT+Fu6O0phGm4Y5UZULL8F7UahOq/JwGAPjJm+V4=
+tinygo.org/x/bluetooth v0.14.0/go.mod h1:YnyJRVX09i+wkFeHpXut0b+qHq+T2WwKBRRiF/scANA=
+tinygo.org/x/drivers v0.34.0 h1:lw8ePJeUSn9oICKBvQXHC9TIE+J00OfXfkGTrpXM9Iw=
+tinygo.org/x/drivers v0.34.0/go.mod h1:ZdErNrApSABdVXjA1RejD67R8SNRI6RKVfYgQDZtKtk=
+tinygo.org/x/tinydraw v0.4.0 h1:U9V0mHz8/jPShKjlh199vCfq1ARFyUOD1b+FfqIwV8c=
+tinygo.org/x/tinydraw v0.4.0/go.mod h1:WCV/EMljTv8w04iAxjv+fRD6/4ffx0afATYeJlN90Yo=
+tinygo.org/x/tinyfont v0.6.0 h1:GibXDSFz6xrWnEDkDRo6vsbOyRw0MVj/eza3zNHMSHs=
+tinygo.org/x/tinyfont v0.6.0/go.mod h1:onflMSkpWl7r7j4MIqhPEVV39pn7yL4N3MOePl3G+G8=