staging: pi433: fix frequency deviation check
PATCH 1/1 staging: pi433: fix frequency deviation check
rf69 datasheet states that frequency deviation must exceed 600 Hz but also that frequency deviation + (bitrate / 2) should be less than equal to 500 kHz to ensure proper modulation.
This patch validates that both conditions are met so RF intersymbol interference is "avoided" where possible.
--- drivers/staging/pi433/rf69.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
drivers/staging/pi433/rf69.c +16 -4
@@ -255,17 +255,29 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)int retval;u64 f_reg;u64 f_step; +u32 bit_rate_reg; +u32 bit_rate;u8 msb;u8 lsb;u64 factor =1000000 ;// to improve precision of calculation -// TODO: Dependency to bitrate -if (deviation <600 || deviation >500000 ) { -dev_dbg (&spi->dev,"set_deviation: illegal input param" ); +// calculate bit rate + bit_rate_reg =rf69_read_reg (spi,REG_BITRATE_MSB ) <<8 ; + bit_rate_reg |=rf69_read_reg (spi,REG_BITRATE_LSB ); + bit_rate =F_OSC / bit_rate_reg; + +/* +* frequency deviation must exceed 600 Hz and but not exceed +* 500kHz when taking bitrate dependency into consideration +* to ensure proper modulation +*/ +if (deviation <600 || (deviation + (bit_rate /2 )) >500000 ) { +dev_dbg (&spi->dev, +"set_deviation: illegal input param: %u" , deviation);return -EINVAL ; } -// calculat f step +// calculate f step f_step =F_OSC * factor;do_div (f_step,524288 );// 524288 = 2^19
Signature · 1 line
2.25.4
Hello Paulo,
thanks for your patch.
Quoted 34 lines · Paulo Miguel Almeida
rf69 datasheet states that frequency deviation must exceed 600 Hz but also that frequency deviation + (bitrate / 2) should be less than equal to 500 kHz to ensure proper modulation.
This patch validates that both conditions are met so RF intersymbol interference is "avoided" where possible.
Signed-off-by Paulo Miguel Almeida <[email protected]>--- drivers/staging/pi433/rf69.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)drivers/staging/pi433/rf69.c +7
-3@@ -255,17 +255,29 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)int retval;u64 f_reg;u64 f_step; +u32 bit_rate_reg; +u32 bit_rate;u8 msb;u8 lsb;u64 factor =1000000 ;// to improve precision of calculation -// TODO: Dependency to bitrate -if (deviation <600 || deviation >500000 ) { -dev_dbg (&spi->dev,"set_deviation: illegal input param" ); +// calculate bit rate + bit_rate_reg =rf69_read_reg (spi,REG_BITRATE_MSB ) <<8 ; + bit_rate_reg |=rf69_read_reg (spi,REG_BITRATE_LSB ); + bit_rate =F_OSC / bit_rate_reg; +
drivers/staging/pi433/rf69.c int rf69_set_deviation(struct spi_device *spi, u32 deviation) · line 278
Quoted 10 lines
drivers/staging/pi433/rf69.c +8
-0+/* +* frequency deviation must exceed 600 Hz and but not exceed +* 500kHz when taking bitrate dependency into consideration +* to ensure proper modulation +*/ +if (deviation <600 || (deviation + (bit_rate /2 )) >500000 ) { +dev_dbg (&spi->dev, +"set_deviation: illegal input param: %u" , deviation);return -EINVAL ; }
this should go in a separate patch IMO
Quoted 10 lines
drivers/staging/pi433/rf69.c +1
-1-// calculat f step +// calculate f step f_step =F_OSC * factor;do_div (f_step,524288 );// 524288 = 2^19 Signature · 1 line
2.25.4
thank you,
fabio
Greg KH
maintainerQuoted 37 lines · Paulo Miguel Almeida
rf69 datasheet states that frequency deviation must exceed 600 Hz but also that frequency deviation + (bitrate / 2) should be less than equal to 500 kHz to ensure proper modulation.
This patch validates that both conditions are met so RF intersymbol interference is "avoided" where possible.
Signed-off-by Paulo Miguel Almeida <[email protected]>--- drivers/staging/pi433/rf69.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)drivers/staging/pi433/rf69.c +10
-3@@ -255,17 +255,29 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)int retval;u64 f_reg;u64 f_step; +u32 bit_rate_reg; +u32 bit_rate;u8 msb;u8 lsb;u64 factor =1000000 ;// to improve precision of calculation -// TODO: Dependency to bitrate -if (deviation <600 || deviation >500000 ) { -dev_dbg (&spi->dev,"set_deviation: illegal input param" ); +// calculate bit rate + bit_rate_reg =rf69_read_reg (spi,REG_BITRATE_MSB ) <<8 ; + bit_rate_reg |=rf69_read_reg (spi,REG_BITRATE_LSB ); + bit_rate =F_OSC / bit_rate_reg; + +/* +* frequency deviation must exceed 600 Hz and but not exceed +* 500kHz when taking bitrate dependency into consideration
drivers/staging/pi433/rf69.c int rf69_set_deviation(struct spi_device *spi, u32 deviation) · line 280
Quoted 10 lines
drivers/staging/pi433/rf69.c +6
-1+* to ensure proper modulation +*/ +if (deviation <600 || (deviation + (bit_rate /2 )) >500000 ) { +dev_dbg (&spi->dev, +"set_deviation: illegal input param: %u" , deviation);return -EINVAL ; } -// calculat f step +// calculate f step
This change should be a separate patch.
thanks,
greg k-h
PATCH v2 1/1 staging: pi433: fix frequency deviation check
rf69 datasheet states that frequency deviation must exceed 600 Hz but also that frequency deviation + (bitrate / 2) should be less than equal to 500 kHz to ensure proper modulation.
This patch validates that both conditions are met so RF intersymbol interference is less likely to happen due to misconfiguration of the uC
---
v2: remove typo correction from this patch - Req Greg k-h, Fabio A.
v1: https://lore.kernel.org/lkml/[email protected]/
--- drivers/staging/pi433/rf69.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
drivers/staging/pi433/rf69.c +15 -3
@@ -255,13 +255,25 @@ int rf69_set_deviation(struct spi_device *spi, u32 deviation)int retval;u64 f_reg;u64 f_step; +u32 bit_rate_reg; +u32 bit_rate;u8 msb;u8 lsb;u64 factor =1000000 ;// to improve precision of calculation -// TODO: Dependency to bitrate -if (deviation <600 || deviation >500000 ) { -dev_dbg (&spi->dev,"set_deviation: illegal input param" ); +// calculate bit rate + bit_rate_reg =rf69_read_reg (spi,REG_BITRATE_MSB ) <<8 ; + bit_rate_reg |=rf69_read_reg (spi,REG_BITRATE_LSB ); + bit_rate =F_OSC / bit_rate_reg; + +/* +* frequency deviation must exceed 600 Hz but not exceed +* 500kHz when taking bitrate dependency into consideration +* to ensure proper modulation +*/ +if (deviation <600 || (deviation + (bit_rate /2 )) >500000 ) { +dev_dbg (&spi->dev, +"set_deviation: illegal input param: %u" , deviation);return -EINVAL ; }
Signature · 1 line
2.25.4
Quoted 6 lines · Greg KH
drivers/staging/pi433/rf69.c int rf69_set_deviation(struct spi_device *spi, u32 deviation) · line 280
Quoted 2 lines · Paulo Miguel Almeida
drivers/staging/pi433/rf69.c +1
-1-// calculat f step +// calculate f step This change should be a separate patch.
Thanks Fabio and Greg for reviewing my patch. I just sent a v2 of this patch with that line untouched.
thanks,
Paulo A.