soypat/lora
1
0
Fork 0
mirror of https://github.com/soypat/lora.git synced 2026-08-16 02:33:24 +00:00
Code Issues Packages Projects Releases Wiki Activity

rename spreadfactor and cleanup type change in sx127x

Browse Source
This commit is contained in:
Joel Wetzell
2026-05-13 08:52:30 -05:00
parent 2ce3e57401
commit aeff7af92a
4 changed files with 52 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files
lora.go
+18 -18
View File
@@ -22,9 +22,9 @@ type Config struct {
// Must be set when working with implicit headers.
MaxImplicitPayloadLength uint8
CodingRate CodingRate
SpreadFactor SpreadFactor // this should probably be called "SpreadingFactor" to be consistent with LoRa terminology
SyncWord uint16 // for new chips sync word is full 16 bits
TxPower int8 // Tx Power in dBm.
SpreadingFactor SpreadingFactor
SyncWord uint16 // for new chips sync word is full 16 bits
TxPower int8 // Tx Power in dBm.
CRC bool
// Low data rate optimisation flag. The use of this flag is mandated when
// the symbol duration exceeds 16ms. Increases reliability at high spreading factors.
@@ -34,9 +34,9 @@ type Config struct {
}
// SymbolPeriod returns the time it takes to transmit a single symbol given the
// current configuration parameters. It depends on Spread factor and Bandwidth.
// current configuration parameters. It depends on Spreading factor and Bandwidth.
func (cfg *Config) SymbolPeriod() time.Duration {
T_s := time.Second * time.Duration(cfg.SpreadFactor.ChipsPerSymbol()) /
T_s := time.Second * time.Duration(cfg.SpreadingFactor.ChipsPerSymbol()) /
time.Duration(cfg.Bandwidth.Hertz())
return T_s
}
@@ -47,7 +47,7 @@ func (cfg *Config) SymbolPeriod() time.Duration {
// - CRC presence (presence == longer)
// - Header type (explicit == longer)
// - Coding rate (proportional)
// - Spread factor (inversely proportional)
// - Spreading factor (inversely proportional)
// - Preamble length (proportional)
// - Low data rate optimisation (presence == longer)
func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
@@ -58,10 +58,10 @@ func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
ih := int64(cfg.HeaderType)
ldr := int64(b2u8(cfg.LDRO))
cr := int64(cfg.CodingRate)
spread := int64(cfg.SpreadFactor)
sf := int64(cfg.SpreadingFactor)
// Page 31 SX1276IMLTRT SEMTECH | Alldatasheet.
Npayload := 8*int64(payloadLength) - 4*spread + 28 + 16*crc - 20*ih
div := 4 * (spread - 2*ldr)
Npayload := 8*int64(payloadLength) - 4*sf + 28 + 16*crc - 20*ih
div := 4 * (sf - 2*ldr)
// Apply Ceil and max with minimal branching.
if Npayload < 0 || div <= 0 {
Npayload = 0
@@ -77,7 +77,7 @@ func (cfg *Config) TimeOnAir(payloadLength int) time.Duration {
// time calculated.
Npayload += 8 + int64(cfg.PreambleLength) + 5
// Calculate LoRa Transmission Parameter Relationship page 28.
chipsPerSymbol := cfg.SpreadFactor.ChipsPerSymbol() // chips per symbol.
chipsPerSymbol := cfg.SpreadingFactor.ChipsPerSymbol() // chips per symbol.
return time.Second * time.Duration(Npayload*int64(chipsPerSymbol)) /
time.Duration(cfg.Bandwidth.Hertz())
}
@@ -110,15 +110,15 @@ const (
CR4_8 CodingRate = 4
)
// SpreadFactor defines the number of chips per symbol. Higher spread factors
// SpreadingFactor defines the number of chips per symbol. Higher spreading factors
// imply longer transmission times but more robust communications.
// The number of chips per symbol is 2^SF, so a spread factor of 8 takes twice
// as long to transmit a symbol as a spread factor of 7.
type SpreadFactor uint8
// The number of chips per symbol is 2^SF, so a spreading factor of 8 takes twice
// as long to transmit a symbol as a spreading factor of 7.
type SpreadingFactor uint8
// Common spread factors. Decide the number of chips per symbol.
// Common spreading factors. Decide the number of chips per symbol.
const (
SF5 SpreadFactor = iota + 5
SF5 SpreadingFactor = iota + 5
SF6
SF7
SF8
@@ -130,9 +130,9 @@ const (
// ChipsPerSymbol returns the number of chips in a symbol. A chip is a subdivision
// of a symbol in the frequency domain rather than the time domain, which is why
// the units of this value is Hz, not Duration. A chip tells tells where to start
// the units of this value is Hz, not Duration. A chip tells where to start
// the frequency sweep for a symbol.
func (sf SpreadFactor) ChipsPerSymbol() int64 {
func (sf SpreadingFactor) ChipsPerSymbol() int64 {
return 1 << sf
}