Merge pull request #43 from plaes/clamp-tx-power

Clamp tx power between driver-specific values
embassy-rs · Nov 15, 2023 · 2bdf5ec · 2bdf5ec
2 parents 9c7c810 + 3c82336
commit 2bdf5ec
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Showing 3 changed files with 23 additions and 22 deletions.
diff --git a/src/mod_params.rs b/src/mod_params.rs
@@ -26,7 +26,6 @@ pub enum RadioError {
     UnavailableCodingRate,
     InvalidBandwidthForFrequency,
     InvalidSF6ExplicitHeaderRequest,
-    InvalidOutputPower,
     InvalidOutputPowerForFrequency,
     HeaderError,
     CRCErrorUnexpected,

diff --git a/src/sx1261_2/mod.rs b/src/sx1261_2/mod.rs
@@ -363,18 +363,22 @@ where
         // TODO: Switch to match so all chip variants are covered
         let chip_type = &self.config.chip;
         if chip_type == &Sx126xVariant::Sx1261 {
-            if !(-17..=15).contains(&output_power) {
-                return Err(RadioError::InvalidOutputPower);
-            }
-            if output_power == 15 {
+            // Clamp power between [-17, 15] dBm
+            let txp = output_power.min(15).max(-17);
+
+            if txp == 15 {
                 if let Some(m_p) = mdltn_params {
                     if m_p.frequency_in_hz < 400_000_000 {
                         return Err(RadioError::InvalidOutputPowerForFrequency);
                     }
                 }
             }
 
-            match output_power {
+            // For SX1261:
+            // if f < 400 MHz, paDutyCycle should not be higher than 0x04,
+            // if f > 400 Mhz, paDutyCycle should not be higher than 0x07.
+            // From Table 13-21: PA Operating Modes with Optimal Settings
+            match txp {
                 15 => {
                     self.set_pa_config(0x06, 0x00, 0x01, 0x01).await?;
                     tx_params_power = 14;
@@ -385,17 +389,16 @@ where
                 }
                 10 => {
                     self.set_pa_config(0x01, 0x00, 0x01, 0x01).await?;
-                    tx_params_power = 14;
+                    tx_params_power = 13;
                 }
                 _ => {
                     self.set_pa_config(0x04, 0x00, 0x01, 0x01).await?;
-                    tx_params_power = output_power as u8;
+                    tx_params_power = txp as u8;
                 }
             }
         } else {
-            if !(-9..=22).contains(&output_power) {
-                return Err(RadioError::InvalidOutputPower);
-            }
+            // Clamp power between [-9, 22] dBm
+            let txp = output_power.min(22).max(-9);
             // Provide better resistance of the SX1262 Tx to antenna mismatch (see DS_SX1261-2_V1.2 datasheet chapter 15.2)
             let mut tx_clamp_cfg = [0x00u8];
             self.intf
@@ -418,7 +421,8 @@ where
             ];
             self.intf.write(&register_and_tx_clamp_cfg, false).await?;
 
-            match output_power {
+            // From Table 13-21: PA Operating Modes with Optimal Settings
+            match txp {
                 22 => {
                     self.set_pa_config(0x04, 0x07, 0x00, 0x01).await?;
                     tx_params_power = 22;
@@ -437,7 +441,7 @@ where
                 }
                 _ => {
                     self.set_pa_config(0x04, 0x07, 0x00, 0x01).await?;
-                    tx_params_power = output_power as u8;
+                    tx_params_power = txp as u8;
                 }
             }
         }

diff --git a/src/sx1276_7_8_9/mod.rs b/src/sx1276_7_8_9/mod.rs
@@ -142,14 +142,13 @@ where
     async fn set_tx_power_sx1276(&mut self, p_out: i32, tx_boost: bool) -> Result<(), RadioError> {
         let pa_reg = Register::RegPaDacSX1276;
         if tx_boost {
-            if !(2..=20).contains(&p_out) {
-                return Err(RadioError::InvalidOutputPower);
-            }
+            // Output via PA_BOOST: [2, 20] dBm
+            let txp = p_out.min(20).max(2);
 
             // Pout=17-(15-OutputPower)
-            let output_power: i32 = p_out - 2;
+            let output_power: i32 = txp - 2;
 
-            if p_out > 17 {
+            if txp > 17 {
                 self.write_register(pa_reg, PaDac::_20DbmOn.value(), false).await?;
                 self.set_ocp(OcpTrim::_240Ma).await?;
             } else {
@@ -163,13 +162,12 @@ where
             )
             .await?;
         } else {
-            if !(-4..=14).contains(&p_out) {
-                return Err(RadioError::InvalidOutputPower);
-            }
+            // Clamp output: [-4, 14] dBm
+            let txp = p_out.min(14).max(-4);
 
             // Pmax=10.8+0.6*MaxPower, where MaxPower is set below as 7 and therefore Pmax is 15
             // Pout=Pmax-(15-OutputPower)
-            let output_power: i32 = p_out;
+            let output_power: i32 = txp;
 
             self.write_register(pa_reg, PaDac::_20DbmOff.value(), false).await?;
             self.set_ocp(OcpTrim::_100Ma).await?;