diff --git a/src/machine/machine_rp2.go b/src/machine/machine_rp2.go
index 6c09fedfe..9afefa538 100644
--- a/src/machine/machine_rp2.go
+++ b/src/machine/machine_rp2.go
@@ -16,6 +16,8 @@ const (
 	// Note: On RP2350, most spinlocks are unusable due to Errata 2
 	_NUMSPINLOCKS         = 32
 	_PICO_SPINLOCK_ID_IRQ = 9
+	// is48Pin notes whether the chip is RP2040 with 32 pins or RP2350 with 48 pins.
+	is48Pin = _NUMBANK0_GPIOS == 48
 )
 
 // UART on the RP2040
diff --git a/src/machine/machine_rp2_2040.go b/src/machine/machine_rp2_2040.go
index 484d8e923..0691b8d77 100644
--- a/src/machine/machine_rp2_2040.go
+++ b/src/machine/machine_rp2_2040.go
@@ -45,6 +45,16 @@ const (
 	PinPIO1
 )
 
+// Analog pins on RP2040.
+const (
+	ADC0 Pin = GPIO26
+	ADC1 Pin = GPIO27
+	ADC2 Pin = GPIO28
+	ADC3 Pin = GPIO29
+
+	thermADC = 30
+)
+
 const (
 	clkGPOUT0 clockIndex = iota // GPIO Muxing 0
 	clkGPOUT1                   // GPIO Muxing 1
diff --git a/src/machine/machine_rp2_2350.go b/src/machine/machine_rp2_2350.go
index 4e12bebe3..32b739c62 100644
--- a/src/machine/machine_rp2_2350.go
+++ b/src/machine/machine_rp2_2350.go
@@ -33,6 +33,16 @@ const (
 		rp.PADS_BANK0_GPIO0_ISO_Msk
 )
 
+// Analog pins on RP2350.
+const (
+	ADC0 Pin = GPIO26
+	ADC1 Pin = GPIO27
+	ADC2 Pin = GPIO28
+	ADC3 Pin = GPIO29
+
+	thermADC = 30
+)
+
 const (
 	PinOutput PinMode = iota
 	PinInput
@@ -126,11 +136,17 @@ func (p Pin) Configure(config PinConfig) {
 		return
 	}
 	p.init()
-	mask := uint32(1) << p
+
 	switch config.Mode {
 	case PinOutput:
 		p.setFunc(fnSIO)
-		rp.SIO.GPIO_OE_SET.Set(mask)
+		if is48Pin && p >= 32 {
+			mask := uint32(1) << (p % 32)
+			rp.SIO.GPIO_HI_OE_SET.Set(mask)
+		} else {
+			mask := uint32(1) << p
+			rp.SIO.GPIO_OE_SET.Set(mask)
+		}
 	case PinInput:
 		p.setFunc(fnSIO)
 		p.pulloff()
diff --git a/src/machine/machine_rp2_2350b.go b/src/machine/machine_rp2_2350b.go
new file mode 100644
index 000000000..c1e4a3a66
--- /dev/null
+++ b/src/machine/machine_rp2_2350b.go
@@ -0,0 +1,48 @@
+//go:build rp2350b
+
+package machine
+
+// RP2350B has additional pins.
+
+const (
+	GPIO30 Pin = 30 // peripherals: PWM7 channel A
+	GPIO31 Pin = 31 // peripherals: PWM7 channel B
+	GPIO32 Pin = 32 // peripherals: PWM8 channel A
+	GPIO33 Pin = 33 // peripherals: PWM8 channel B
+	GPIO34 Pin = 34 // peripherals: PWM9 channel A
+	GPIO35 Pin = 35 // peripherals: PWM9 channel B
+	GPIO36 Pin = 36 // peripherals: PWM10 channel A
+	GPIO37 Pin = 37 // peripherals: PWM10 channel B
+	GPIO38 Pin = 38 // peripherals: PWM11 channel A
+	GPIO39 Pin = 39 // peripherals: PWM11 channel B
+	GPIO40 Pin = 40 // peripherals: PWM8 channel A
+	GPIO41 Pin = 41 // peripherals: PWM8 channel B
+	GPIO42 Pin = 42 // peripherals: PWM9 channel A
+	GPIO43 Pin = 43 // peripherals: PWM9 channel B
+	GPIO44 Pin = 44 // peripherals: PWM10 channel A
+	GPIO45 Pin = 45 // peripherals: PWM10 channel B
+	GPIO46 Pin = 46 // peripherals: PWM11 channel A
+	GPIO47 Pin = 47 // peripherals: PWM11 channel B
+)
+
+// Analog pins on 2350b.
+const (
+	ADC0 Pin = GPIO40
+	ADC1 Pin = GPIO41
+	ADC2 Pin = GPIO42
+	ADC3 Pin = GPIO43
+	ADC4 Pin = GPIO44
+	ADC5 Pin = GPIO45
+	ADC6 Pin = GPIO46
+	ADC7 Pin = GPIO47
+
+	thermADC = 48
+)
+
+// Additional PWMs on the RP2350B.
+var (
+	PWM8  = getPWMGroup(8)
+	PWM9  = getPWMGroup(9)
+	PWM10 = getPWMGroup(10)
+	PWM11 = getPWMGroup(11)
+)
diff --git a/src/machine/machine_rp2_adc.go b/src/machine/machine_rp2_adc.go
index 13504d719..fc9a8268e 100644
--- a/src/machine/machine_rp2_adc.go
+++ b/src/machine/machine_rp2_adc.go
@@ -11,15 +11,6 @@ import (
 // ADCChannel is the ADC peripheral mux channel. 0-4.
 type ADCChannel uint8
 
-// ADC channels. Only ADC_TEMP_SENSOR is public. The other channels are accessed via Machine.ADC objects
-const (
-	adc0_CH ADCChannel = iota
-	adc1_CH
-	adc2_CH
-	adc3_CH       // Note: GPIO29 not broken out on pico board
-	adcTempSensor // Internal temperature sensor channel
-)
-
 // Used to serialise ADC sampling
 var adcLock sync.Mutex
 
@@ -58,20 +49,10 @@ func (a ADC) Get() uint16 {
 
 // GetADCChannel returns the channel associated with the ADC pin.
 func (a ADC) GetADCChannel() (c ADCChannel, err error) {
-	err = nil
-	switch a.Pin {
-	case ADC0:
-		c = adc0_CH
-	case ADC1:
-		c = adc1_CH
-	case ADC2:
-		c = adc2_CH
-	case ADC3:
-		c = adc3_CH
-	default:
-		err = errors.New("no ADC channel for pin value")
+	if a.Pin < ADC0 {
+		return 0, errors.New("no ADC channel for pin value")
 	}
-	return c, err
+	return ADCChannel(a.Pin - ADC0), nil
 }
 
 // Configure sets the channel's associated pin to analog input mode.
@@ -113,12 +94,12 @@ func ReadTemperature() (millicelsius int32) {
 	if rp.ADC.CS.Get()&rp.ADC_CS_EN == 0 {
 		InitADC()
 	}
-
+	thermChan, _ := ADC{Pin: thermADC}.GetADCChannel()
 	// Enable temperature sensor bias source
 	rp.ADC.CS.SetBits(rp.ADC_CS_TS_EN)
 
 	// T = 27 - (ADC_voltage - 0.706)/0.001721
-	return (27000<<16 - (int32(adcTempSensor.getVoltage())-706<<16)*581) >> 16
+	return (27000<<16 - (int32(thermChan.getVoltage())-706<<16)*581) >> 16
 }
 
 // waitForReady spins waiting for the ADC peripheral to become ready.
@@ -129,18 +110,5 @@ func waitForReady() {
 
 // The Pin method returns the GPIO Pin associated with the ADC mux channel, if it has one.
 func (c ADCChannel) Pin() (p Pin, err error) {
-	err = nil
-	switch c {
-	case adc0_CH:
-		p = ADC0
-	case adc1_CH:
-		p = ADC1
-	case adc2_CH:
-		p = ADC2
-	case adc3_CH:
-		p = ADC3
-	default:
-		err = errors.New("no associated pin for channel")
-	}
-	return p, err
+	return Pin(c) + ADC0, nil
 }
diff --git a/src/machine/machine_rp2_clocks.go b/src/machine/machine_rp2_clocks.go
index cc152a7f8..ba5bb67af 100644
--- a/src/machine/machine_rp2_clocks.go
+++ b/src/machine/machine_rp2_clocks.go
@@ -13,12 +13,6 @@ func CPUFrequency() uint32 {
 	return 125 * MHz
 }
 
-// Returns the period of a clock cycle for the raspberry pi pico in nanoseconds.
-// Used in PWM API.
-func cpuPeriod() uint32 {
-	return 1e9 / CPUFrequency()
-}
-
 // clockIndex identifies a hardware clock
 type clockIndex uint8
 
diff --git a/src/machine/machine_rp2_gpio.go b/src/machine/machine_rp2_gpio.go
index d49d12f2b..6854f8aad 100644
--- a/src/machine/machine_rp2_gpio.go
+++ b/src/machine/machine_rp2_gpio.go
@@ -63,8 +63,13 @@ func (p Pin) PortMaskSet() (*uint32, uint32) {
 
 // set drives the pin high
 func (p Pin) set() {
-	mask := uint32(1) << p
-	rp.SIO.GPIO_OUT_SET.Set(mask)
+	if is48Pin && p >= 32 {
+		mask := uint32(1) << (p % 32)
+		rp.SIO.GPIO_HI_OUT_SET.Set(mask)
+	} else {
+		mask := uint32(1) << p
+		rp.SIO.GPIO_OUT_SET.Set(mask)
+	}
 }
 
 func (p Pin) PortMaskClear() (*uint32, uint32) {
@@ -73,18 +78,31 @@ func (p Pin) PortMaskClear() (*uint32, uint32) {
 
 // clr drives the pin low
 func (p Pin) clr() {
-	mask := uint32(1) << p
-	rp.SIO.GPIO_OUT_CLR.Set(mask)
+	if is48Pin && p >= 32 {
+		mask := uint32(1) << (p % 32)
+		rp.SIO.GPIO_HI_OUT_CLR.Set(mask)
+	} else {
+		mask := uint32(1) << p
+		rp.SIO.GPIO_OUT_CLR.Set(mask)
+	}
 }
 
 // xor toggles the pin
 func (p Pin) xor() {
-	mask := uint32(1) << p
-	rp.SIO.GPIO_OUT_XOR.Set(mask)
+	if is48Pin && p >= 32 {
+		mask := uint32(1) << (p % 32)
+		rp.SIO.GPIO_HI_OUT_XOR.Set(mask)
+	} else {
+		mask := uint32(1) << p
+		rp.SIO.GPIO_OUT_XOR.Set(mask)
+	}
 }
 
 // get returns the pin value
 func (p Pin) get() bool {
+	if is48Pin && p >= 32 {
+		return rp.SIO.GPIO_HI_IN.HasBits(1 << (p % 32))
+	}
 	return rp.SIO.GPIO_IN.HasBits(1 << p)
 }
 
@@ -134,8 +152,13 @@ func (p Pin) setFunc(fn pinFunc) {
 
 // init initializes the gpio pin
 func (p Pin) init() {
-	mask := uint32(1) << p
-	rp.SIO.GPIO_OE_CLR.Set(mask)
+	if is48Pin && p >= 32 {
+		mask := uint32(1) << (p % 32)
+		rp.SIO.GPIO_HI_OE_CLR.Set(mask)
+	} else {
+		mask := uint32(1) << p
+		rp.SIO.GPIO_OE_CLR.Set(mask)
+	}
 	p.clr()
 }
 
diff --git a/src/machine/machine_rp2_pins.go b/src/machine/machine_rp2_pins.go
index 93f2d50a0..43b31f938 100644
--- a/src/machine/machine_rp2_pins.go
+++ b/src/machine/machine_rp2_pins.go
@@ -1,4 +1,4 @@
-//go:build rp2040 || rp2350 || ae_rp2040 || badger2040 || challenger_rp2040 || feather_rp2040 || gopher_badge || kb2040 || macropad_rp2040 || nano_rp2040 || pico || qtpy_rp2040 || thingplus_rp2040 || thumby || tufty2040 || waveshare_rp2040_zero || xiao_rp2040
+//go:build rp2040 || rp2350 || gopher_badge
 
 package machine
 
@@ -34,10 +34,4 @@ const (
 	GPIO27 Pin = 27 // peripherals: PWM5 channel B
 	GPIO28 Pin = 28 // peripherals: PWM6 channel A
 	GPIO29 Pin = 29 // peripherals: PWM6 channel B
-
-	// Analog pins
-	ADC0 Pin = GPIO26
-	ADC1 Pin = GPIO27
-	ADC2 Pin = GPIO28
-	ADC3 Pin = GPIO29
 )
diff --git a/src/machine/machine_rp2040_pwm.go b/src/machine/machine_rp2_pwm.go
similarity index 95%
rename from src/machine/machine_rp2040_pwm.go
rename to src/machine/machine_rp2_pwm.go
index f72d6dd03..1a511daf1 100644
--- a/src/machine/machine_rp2040_pwm.go
+++ b/src/machine/machine_rp2_pwm.go
@@ -1,4 +1,4 @@
-//go:build rp2040
+//go:build rp2040 || rp2350
 
 package machine
 
@@ -15,7 +15,7 @@ var (
 )
 
 const (
-	maxPWMPins = 29
+	maxPWMPins = _NUMBANK0_GPIOS - 1
 )
 
 // pwmGroup is one PWM peripheral, which consists of a counter and two output
@@ -146,12 +146,13 @@ func (p *pwmGroup) Counter() uint32 {
 
 // Period returns the used PWM period in nanoseconds.
 func (p *pwmGroup) Period() uint64 {
-	periodPerCycle := cpuPeriod()
+	freq := CPUFrequency()
 	top := p.getWrap()
 	phc := p.getPhaseCorrect()
 	Int, frac := p.getClockDiv()
-	// Line below can overflow if operations done without care.
-	return (16*uint64(Int) + uint64(frac)) * uint64((top+1)*(phc+1)*periodPerCycle) / 16 // cycles = (TOP+1) * (CSRPHCorrect + 1) * (DIV_INT + DIV_FRAC/16)
+	// Lines below can overflow if operations done without care.
+	term2 := 16 * uint64((top+1)*(phc+1)) * 1e9 / uint64(freq) // 1e9/freq == CPU period in nanoseconds.
+	return (uint64(Int) + uint64(frac)) * term2 / 16           // cycles = (TOP+1) * (CSRPHCorrect + 1) * (DIV_INT + DIV_FRAC/16)
 }
 
 // SetInverting sets whether to invert the output of this channel.
@@ -279,9 +280,9 @@ func (pwm *pwmGroup) setPeriod(period uint64) error {
 	//  DIV_INT + DIV_FRAC/16 = cycles / ( (TOP+1) * (CSRPHCorrect+1) )  // DIV_FRAC/16 is always 0 in this equation
 	// where cycles must be converted to time:
 	//  target_period = cycles * period_per_cycle ==> cycles = target_period/period_per_cycle
-	periodPerCycle := uint64(cpuPeriod())
+	freq := uint64(CPUFrequency())
 	phc := uint64(pwm.getPhaseCorrect())
-	rhs := 16 * period / ((1 + phc) * periodPerCycle * (1 + topStart)) // right-hand-side of equation, scaled so frac is not divided
+	rhs := 16e9 * period / ((1 + phc) * freq * (1 + topStart)) // right-hand-side of equation, scaled so frac is not divided
 	whole := rhs / 16
 	frac := rhs % 16
 	switch {
@@ -296,7 +297,7 @@ func (pwm *pwmGroup) setPeriod(period uint64) error {
 
 	// Step 2 is acquiring a better top value. Clearing the equation:
 	// TOP =  cycles / ( (DIVINT+DIVFRAC/16) * (CSRPHCorrect+1) ) - 1
-	top := 16*period/((16*whole+frac)*periodPerCycle*(1+phc)) - 1
+	top := 16e9*period/((16*whole+frac)*freq*(1+phc)) - 1
 	if top > maxTop {
 		top = maxTop
 	}
@@ -400,6 +401,9 @@ func (pwm *pwmGroup) getClockDiv() (Int, frac uint8) {
 // pwmGPIOToSlice Determine the PWM channel that is attached to the specified GPIO.
 // gpio must be less than 30. Returns the PWM slice number that controls the specified GPIO.
 func pwmGPIOToSlice(gpio Pin) (slicenum uint8) {
+	if is48Pin && gpio >= 32 {
+		return uint8(8 + ((gpio-32)/2)%4)
+	}
 	return (uint8(gpio) >> 1) & 7
 }
 
diff --git a/targets/rp2350b.json b/targets/rp2350b.json
new file mode 100644
index 000000000..5db4d4849
--- /dev/null
+++ b/targets/rp2350b.json
@@ -0,0 +1,5 @@
+{
+    "inherits": ["rp2350"],
+    "build-tags": ["rp2350b"],
+    "serial-port": ["2e8a:000f"]
+}
\ No newline at end of file