diff --git a/ili9341/ili9341.go b/ili9341/ili9341.go
index 6673fcf..fe53dcc 100644
--- a/ili9341/ili9341.go
+++ b/ili9341/ili9341.go
@@ -300,7 +300,9 @@ func (d *Device) sendCommand(cmd byte, data []byte) {
 	d.dc.Low()
 	d.driver.write8(cmd)
 	d.dc.High()
-	d.driver.write8sl(data)
+	if data != nil && len(data) > 0 {
+		d.driver.write8sl(data)
+	}
 	d.endWrite()
 }
 
diff --git a/ili9341/spi_atsamd51.go b/ili9341/spi_atsamd51.go
index ca31db6..76ade44 100644
--- a/ili9341/spi_atsamd51.go
+++ b/ili9341/spi_atsamd51.go
@@ -3,7 +3,6 @@
 package ili9341
 
 import (
-	"device/sam"
 	"machine"
 )
 
@@ -11,6 +10,8 @@ type spiDriver struct {
 	bus machine.SPI
 }
 
+var txBuf [2]uint8
+
 func NewSPI(bus machine.SPI, dc, cs, rst machine.Pin) *Device {
 	return &Device{
 		dc:  dc,
@@ -27,90 +28,31 @@ func (pd *spiDriver) configure(config *Config) {
 }
 
 func (pd *spiDriver) write8(b byte) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
-	for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-	}
-	pd.bus.Bus.DATA.Set(uint32(b))
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
-	}
+	pd.bus.Transfer(b)
 }
 
 func (pd *spiDriver) write8n(b byte, n int) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
-	for i, c := 0, n; i < c; i++ {
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(b))
-	}
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
-	}
+	panic("not impl")
 }
 
 func (pd *spiDriver) write8sl(b []byte) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
-	for i, c := 0, len(b); i < c; i++ {
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(b[i]))
-	}
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
-	}
+	pd.bus.Tx(b, nil)
 }
 
 func (pd *spiDriver) write16(data uint16) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
-	for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-	}
-	pd.bus.Bus.DATA.Set(uint32(uint8(data >> 8)))
-	for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-	}
-	pd.bus.Bus.DATA.Set(uint32(uint8(data)))
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
-	}
+	txBuf[0] = uint8(data >> 8)
+	txBuf[1] = uint8(data)
+	pd.bus.Tx(txBuf[:], nil)
 }
 
 func (pd *spiDriver) write16n(data uint16, n int) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
-	for i := 0; i < n; i++ {
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(uint8(data >> 8)))
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(uint8(data)))
-	}
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
+	for i, c := 0, n; i < c; i++ {
+		pd.write16(data)
 	}
 }
 
 func (pd *spiDriver) write16sl(data []uint16) {
-	pd.bus.Bus.CTRLB.ClearBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-
 	for i, c := 0, len(data); i < c; i++ {
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(uint8(data[i] >> 8)))
-		for !pd.bus.Bus.INTFLAG.HasBits(sam.SERCOM_SPIM_INTFLAG_DRE) {
-		}
-		pd.bus.Bus.DATA.Set(uint32(uint8(data[i])))
-	}
-
-	pd.bus.Bus.CTRLB.SetBits(sam.SERCOM_SPIM_CTRLB_RXEN)
-	for pd.bus.Bus.SYNCBUSY.HasBits(sam.SERCOM_SPIM_SYNCBUSY_CTRLB) {
+		pd.write16(data[i])
 	}
 }