diff --git a/go.mod b/go.mod
index 405de2ca..64668f6c 100644
--- a/go.mod
+++ b/go.mod
@@ -4,7 +4,10 @@ go 1.11
 
 require (
 	github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2
+	github.com/creack/goselect v0.1.0 // indirect
 	github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46
+	go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45
+	golang.org/x/sys v0.0.0-20191010194322-b09406accb47 // indirect
 	golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef
 	tinygo.org/x/go-llvm v0.0.0-20190818154551-95bc4ffe1add
 )
diff --git a/go.sum b/go.sum
index 5f744434..341c3e5b 100644
--- a/go.sum
+++ b/go.sum
@@ -1,11 +1,17 @@
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2 h1:oMCHnXa6CCCafdPDbMh/lWRhRByN0VFLvv+g+ayx1SI=
 github.com/blakesmith/ar v0.0.0-20150311145944-8bd4349a67f2/go.mod h1:PkYb9DJNAwrSvRx5DYA+gUcOIgTGVMNkfSCbZM8cWpI=
+github.com/creack/goselect v0.1.0 h1:4QiXIhcpSQF50XGaBsFzesjwX/1qOY5bOveQPmN9CXY=
+github.com/creack/goselect v0.1.0/go.mod h1:gHrIcH/9UZDn2qgeTUeW5K9eZsVYCH6/60J/FHysWyE=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46 h1:wXG2bA8fO7Vv7lLk2PihFMTqmbT173Tje39oKzQ50Mo=
 github.com/marcinbor85/gohex v0.0.0-20180128172054-7a43cd876e46/go.mod h1:Pb6XcsXyropB9LNHhnqaknG/vEwYztLkQzVCHv8sQ3M=
+go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45 h1:mACY1anK6HNCZtm/DK2Rf2ZPHggVqeB0+7rY9Gl6wyI=
+go.bug.st/serial.v1 v0.0.0-20180827123349-5f7892a7bb45/go.mod h1:dRSl/CVCTf56CkXgJMDOdSwNfo2g1orOGE/gBGdvjZw=
 golang.org/x/net v0.0.0-20180724234803-3673e40ba225/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/net v0.0.0-20190213061140-3a22650c66bd/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20191010194322-b09406accb47 h1:/XfQ9z7ib8eEJX2hdgFTZJ/ntt0swNk5oYBziWeTCvY=
+golang.org/x/sys v0.0.0-20191010194322-b09406accb47/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef h1:ymc9FeDom3RIEA3coKokSllBB1hRcMT0tZ1W3Jf9Ids=
 golang.org/x/tools v0.0.0-20190227180812-8dcc6e70cdef/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
diff --git a/main.go b/main.go
index 0778de46..3c169bf9 100644
--- a/main.go
+++ b/main.go
@@ -15,10 +15,13 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/tinygo-org/tinygo/compiler"
 	"github.com/tinygo-org/tinygo/interp"
 	"github.com/tinygo-org/tinygo/loader"
+
+	serial "go.bug.st/serial.v1"
 )
 
 // commandError is an error type to wrap os/exec.Command errors. This provides
@@ -418,6 +421,16 @@ func Flash(pkgName, target, port string, config *BuildConfig) error {
 			return errors.New("no flash command specified - did you miss a -target flag?")
 		}
 
+		// do we need port reset to put MCU into bootloader mode?
+		if spec.PortReset == "true" {
+			err := touchSerialPortAt1200bps(port)
+			if err != nil {
+				return &commandError{"failed to reset port", tmppath, err}
+			}
+			// give the target MCU a chance to restart into bootloader
+			time.Sleep(3 * time.Second)
+		}
+
 		// Create the command.
 		flashCmd := spec.Flasher
 		fileToken := "{" + fileExt[1:] + "}"
@@ -549,6 +562,18 @@ func Run(pkgName, target string, config *BuildConfig) error {
 	})
 }
 
+func touchSerialPortAt1200bps(port string) error {
+	// Open port
+	p, err := serial.Open(port, &serial.Mode{BaudRate: 1200})
+	if err != nil {
+		return fmt.Errorf("opening port: %s", err)
+	}
+	defer p.Close()
+
+	p.SetDTR(false)
+	return nil
+}
+
 // parseSize converts a human-readable size (with k/m/g suffix) into a plain
 // number.
 func parseSize(s string) (int64, error) {
diff --git a/target.go b/target.go
index ad701e83..c3fea39f 100644
--- a/target.go
+++ b/target.go
@@ -46,6 +46,7 @@ type TargetSpec struct {
 	OCDDaemon  []string `json:"ocd-daemon"`
 	GDB        string   `json:"gdb"`
 	GDBCmds    []string `json:"gdb-initial-cmds"`
+	PortReset  string   `json:"flash-1200-bps-reset"`
 }
 
 // copyProperties copies all properties that are set in spec2 into itself.
@@ -100,6 +101,9 @@ func (spec *TargetSpec) copyProperties(spec2 *TargetSpec) {
 	if len(spec2.GDBCmds) != 0 {
 		spec.GDBCmds = spec2.GDBCmds
 	}
+	if spec2.PortReset != "" {
+		spec.PortReset = spec2.PortReset
+	}
 }
 
 // load reads a target specification from the JSON in the given io.Reader. It
@@ -237,6 +241,7 @@ func defaultTarget(goos, goarch, triple string) (*TargetSpec, error) {
 		Linker:    "cc",
 		GDB:       "gdb",
 		GDBCmds:   []string{"run"},
+		PortReset: "false",
 	}
 	if goos == "darwin" {
 		spec.LDFlags = append(spec.LDFlags, "-Wl,-dead_strip")
diff --git a/targets/arduino-nano33.json b/targets/arduino-nano33.json
index eaad5879..839fd7c1 100644
--- a/targets/arduino-nano33.json
+++ b/targets/arduino-nano33.json
@@ -1,5 +1,6 @@
 {
     "inherits": ["atsamd21g18a"],
     "build-tags": ["sam", "atsamd21g18a", "arduino_nano33"],
-    "flash": "bossac -d -i -e -w -v -R --port={port} --offset=0x2000 {bin}"
+    "flash": "bossac -d -i -e -w -v -R --port={port} --offset=0x2000 {bin}",
+    "flash-1200-bps-reset": "true"
 }