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Suggestions by pato for GPS UBX support #831

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Merged
deadprogram merged 2 commits into from
Jan 8, 2026
Merged

Suggestions by pato for GPS UBX support #831

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6f8c4aa
apply suggestions by pato
soypat Jan 5, 2026
297c2c0
whoopsie on inverted condition
soypat Jan 6, 2026
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4 changes: 1 addition & 3 deletions gps/gps.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,19 +31,18 @@ const (

// Device wraps a connection to a GPS device.
type Device struct {
buffer []byte
bufIdx int
sentence strings.Builder
uart drivers.UART
bus drivers.I2C
address uint16
buffer [bufferSize]byte
}

// NewUART creates a new UART GPS connection. The UART must already be configured.
func NewUART(uart drivers.UART) Device {
return Device{
uart: uart,
buffer: make([]byte, bufferSize),
bufIdx: bufferSize,
sentence: strings.Builder{},
}
Expand All @@ -60,7 +59,6 @@ func NewI2CWithAddress(bus drivers.I2C, i2cAddress uint16) Device {
return Device{
bus: bus,
address: i2cAddress,
buffer: make([]byte, bufferSize),
bufIdx: bufferSize,
sentence: strings.Builder{},
}
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106 changes: 47 additions & 59 deletions gps/ublox.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,7 @@ import (

// FlightModeCmd is a UBX-CFG-NAV5 command to set the GPS into
// flight mode (airborne <1g)
var FlightModeCmd = CfgNav5{
var flightModeCmd = CfgNav5{
Mask: CfgNav5Dyn | CfgNav5MinEl | CfgNav5PosFixMode,
DynModel: DynModeAirborne1g, // Airborne with <1g acceleration
FixMode: FixModeAuto, // Auto 2D/3D
Expand All @@ -28,123 +28,110 @@ var FlightModeCmd = CfgNav5{
}

// SetFlightMode sends UBX-CFG-NAV5 command to set GPS into flight mode
func SetFlightMode(d Device) (err error) {
if _, err = FlightModeCmd.Write(d.buffer[:]); err != nil {
return err
}
err = SendCommand(d, d.buffer[:])
return err
func (d *Device) SetFlightMode() (err error) {
flightModeCmd.Put42Bytes(d.buffer[:])
return d.SendCommand(d.buffer[:42])
}

var (
// GGA (time, lat/lng, altitude)
MessageRateGGACmd = CfgMsg1{
messageRateGGACmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x00,
Rate: 1, // Every position fix
}
// GLL (time, lat/lng)
MessageRateGLLCmd = CfgMsg1{
messageRateGLLCmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x01,
Rate: 0, // Disabled
}
// GSA (satellite id list)
MessageRateGSACmd = CfgMsg1{
messageRateGSACmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x02,
Rate: 1, // Every position fix
}
// GSV (satellite locations)
MessageRateGSVCmd = CfgMsg1{
messageRateGSVCmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x03,
Rate: 1, // Every position fix
}
// RMC (time, lat/lng, speed, course)
MessageRateRMCCmd = CfgMsg1{
messageRateRMCCmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x04,
Rate: 1, // Every position fix
}
// VTG (speed, course)
MessageRateVTGCmd = CfgMsg1{
messageRateVTGCmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x05,
Rate: 0, // Disabled
}
// ZDA (time, timezone)
MessageRateZDACmd = CfgMsg1{
messageRateZDACmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x08,
Rate: 0, // Disabled
}
// TXT (text transmission)
MessageRateTXTCmd = CfgMsg1{
messageRateTXTCmd = CfgMsg1{
MsgClass: 0xF0,
MsgID: 0x41,
Rate: 0, // Disabled
}
)

// SetMessageRatesMinimal configures the GPS to output a minimal set of NMEA sentences
func SetMessageRatesMinimal(d Device) (err error) {
func SetMessageRatesMinimal(d *Device) (err error) {
commands := []CfgMsg1{
MessageRateGSACmd,
MessageRateGGACmd,
MessageRateGLLCmd,
MessageRateGSVCmd,
MessageRateRMCCmd,
MessageRateVTGCmd,
MessageRateZDACmd,
MessageRateTXTCmd,
}

for _, cmd := range commands {
if _, err = cmd.Write(d.buffer[:]); err != nil {
return err
}
if err = SendCommand(d, d.buffer[:]); err != nil {
return err
}
}

return nil
messageRateGSACmd,
messageRateGGACmd,
messageRateGLLCmd,
messageRateGSVCmd,
messageRateRMCCmd,
messageRateVTGCmd,
messageRateZDACmd,
messageRateTXTCmd,
}
return setCfg1s(d, commands)
}

// SetMessageRatesAllEnabled configures the GPS to output all NMEA sentences
func SetMessageRatesAllEnabled(d Device) (err error) {
func SetMessageRatesAllEnabled(d *Device) (err error) {
commands := []CfgMsg1{
MessageRateGSACmd,
MessageRateGGACmd,
MessageRateGLLCmd,
MessageRateGSVCmd,
MessageRateRMCCmd,
MessageRateVTGCmd,
MessageRateZDACmd,
MessageRateTXTCmd,
}
messageRateGSACmd,
messageRateGGACmd,
messageRateGLLCmd,
messageRateGSVCmd,
messageRateRMCCmd,
messageRateVTGCmd,
messageRateZDACmd,
messageRateTXTCmd,
}
return setCfg1s(d, commands)
}

func setCfg1s(d *Device, commands []CfgMsg1) (err error) {
var buf [9]byte
for _, cmd := range commands {
cmd.Rate = 1 // Enable all messages at 1 Hz
if _, err = cmd.Write(d.buffer[:]); err != nil {
return err
}
if err = SendCommand(d, d.buffer[:]); err != nil {
cmd.Put9Bytes(buf[:9])
if err = d.SendCommand(buf[:9]); err != nil {
return err
}
}

return nil
}

// GNSSDisableCmd is a UBX-CFG-GNSS command to disable all GNSS but GPS
// gnssDisableCmd is a UBX-CFG-GNSS command to disable all GNSS but GPS
// Needed for MAX8's, not needed for MAX7
var GNSSDisableCmd = CfgGnss{
var gnssDisableCmd = CfgGnss{
MsgVer: 0x00,
NumTrkChHw: 0x20, // 32 channels
NumTrkChUse: 0x20,
ConfigBlocks: []*CfgGnssConfigBlocksType{
ConfigBlocks: []CfgGnssConfigBlocksType{
{GnssId: 0, ResTrkCh: 8, MaxTrkCh: 16, Flags: CfgGnssEnable | 0x010000}, // GPS enabled
{GnssId: 1, ResTrkCh: 1, MaxTrkCh: 3, Flags: 0x010000}, // SBAS disabled
{GnssId: 3, ResTrkCh: 8, MaxTrkCh: 16, Flags: 0x010000}, // BeiDou disabled
Expand All @@ -154,15 +141,16 @@ var GNSSDisableCmd = CfgGnss{
}

// SetGNSSDisable sends UBX-CFG-GNSS command to disable all GNSS but GPS
func SetGNSSDisable(d Device) (err error) {
if _, err = GNSSDisableCmd.Write(d.buffer[:]); err != nil {
func (d *Device) SetGNSSDisable() (err error) {
err = gnssDisableCmd.Put(d.buffer[:])
if err != nil {
return err
}
return SendCommand(d, d.buffer[:])
return d.SendCommand(d.buffer[:])
}

// SendCommand sends a UBX command and waits for ACK/NAK response
func SendCommand(d Device, command []byte) error {
func (d *Device) SendCommand(command []byte) error {
// Calculate and append checksum
checksummed := appendChecksum(command)
d.WriteBytes(checksummed)
Expand Down
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