seesaw: remove delay from Read(...)

Author: thomasrichner-oviva

examples/seesaw/main.go

@@ -4,6 +4,7 @@ import (
 	"machine"
 	"strconv"
 	"time"
+
 	"tinygo.org/x/drivers/seesaw"
 )
 
@@ -18,8 +19,11 @@ func main() {
 
 	dev.Address = 0x36
 
+	// the soil sensor is especially slow, let's give it some more time
+	dev.ReadDelay = readDelay
+
 	var buf [2]byte
-	err := dev.Read(seesaw.ModuleTouchBase, seesaw.FunctionTouchChannelOffset, buf[:], readDelay)
+	err := dev.Read(seesaw.ModuleTouchBase, seesaw.FunctionTouchChannelOffset, buf[:])
 	if err != nil {
 		panic(err)
 	}

seesaw/seesaw.go

@@ -18,25 +18,26 @@ import (
 // built on top of it come with their own respective default addresses.
 const DefaultAddress = 0x49
 
-// empirically determined standardDelay, the one from the official library seems to be too short (250us)
-const defaultDelay = 100 * time.Millisecond
+// DefaultReadDelay is an empirically determined delay used when reading from the device,
+// the one from the official library seems to be too short (250us)
+const DefaultReadDelay = 100 * time.Millisecond
 
 const (
 	seesawHwIdCodeSAMD09  = 0x55 // HW ID code for SAMD09
 	seesawHwIdCodeTINY8x7 = 0x87 // HW ID code for ATtiny817
 )
 
 type Device struct {
-	bus           drivers.I2C
-	Address       uint16
-	standardDelay time.Duration
+	bus       drivers.I2C
+	Address   uint16
+	ReadDelay time.Duration
 }
 
 func New(bus drivers.I2C) *Device {
 	return &Device{
-		bus:           bus,
-		Address:       DefaultAddress,
-		standardDelay: defaultDelay,
+		bus:       bus,
+		Address:   DefaultAddress,
+		ReadDelay: DefaultReadDelay,
 	}
 }
 
@@ -92,16 +93,16 @@ func (d *Device) WriteRegister(module ModuleBaseAddress, function FunctionAddres
 // ReadRegister reads a single register from seesaw
 func (d *Device) ReadRegister(module ModuleBaseAddress, function FunctionAddress) (byte, error) {
 	var buf [1]byte
-	err := d.Read(module, function, buf[:], d.standardDelay)
+	err := d.Read(module, function, buf[:])
 	if err != nil {
 		return 0, err
 	}
 	return buf[0], nil
 }
 
-// Read reads a number of bytes from the device after sending the read command and waiting 'standardDelay'. The delays depend
+// Read reads a number of bytes from the device after sending the read command and waiting 'ReadDelay'. The delays depend
 // on the module and function and are documented in the seesaw datasheet
-func (d *Device) Read(module ModuleBaseAddress, function FunctionAddress, buf []byte, delay time.Duration) error {
+func (d *Device) Read(module ModuleBaseAddress, function FunctionAddress, buf []byte) error {
 	var cmd [2]byte
 	cmd[0] = byte(module)
 	cmd[1] = byte(function)
@@ -113,7 +114,7 @@ func (d *Device) Read(module ModuleBaseAddress, function FunctionAddress, buf []
 
 	// This is needed for the client seesaw device to flush its RX buffer and process the command.
 	// See seesaw datasheet for timings for specific modules.
-	time.Sleep(delay)
+	time.Sleep(d.ReadDelay)
 
 	return d.bus.Tx(d.Address, nil, buf)
 }

seesaw/seesaw_test.go

@@ -2,7 +2,6 @@ package seesaw
 
 import (
 	"testing"
-	"time"
 
 	"github.com/frankban/quicktest"
 )
@@ -57,9 +56,10 @@ func TestDevice_Read(t *testing.T) {
 	)
 
 	sut := New(mocked)
+	sut.ReadDelay = 0
 
 	var buf [5]byte
-	err := sut.Read(ModuleTouchBase, FunctionTouchChannelOffset, buf[:], time.Nanosecond)
+	err := sut.Read(ModuleTouchBase, FunctionTouchChannelOffset, buf[:])
 
 	qt := quicktest.New(t)
 	qt.Assert(err, quicktest.IsNil)