From 8b3d6dd4e72f8d5a98055756eac6f2a3212ad453 Mon Sep 17 00:00:00 2001
From: Sven Gothel <sgothel@jausoft.com>
Date: Fri, 24 Nov 2023 09:21:12 +0100
Subject: BTDevice: API Doc: Detail RSSI and Tx Power Level

---
 api/direct_bt/BTDevice.hpp | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

(limited to 'api')

diff --git a/api/direct_bt/BTDevice.hpp b/api/direct_bt/BTDevice.hpp
index c42a8b88..0d8c52c1 100644
--- a/api/direct_bt/BTDevice.hpp
+++ b/api/direct_bt/BTDevice.hpp
@@ -398,10 +398,41 @@ namespace direct_bt {
              */
             BDAddressAndType const & getVisibleAddressAndType() const noexcept { return visibleAddressAndType; }
 
-            /** Return RSSI of device as recognized at discovery and connect. */
+            /**
+             * Returns Received Signal Strength Indicator (RSSI)
+             * in dBm with ±6 dB accuracy of device as recognized at discovery and connect.
+             * <p>
+             * BT Core Spec v5.2: Vol 4, Part E HCI: 7.5.4 Read RSSI command
+             * </p>
+             * <p>
+             * Any positive RSSI value indicates how many dB the RSSI is above the upper limit,
+             * any negative value indicates how many dB the RSSI is below the lower limit.
+             * The value zero indicates that the RSSI is inside the Golden Receive Power Range.
+             * </p>
+             * <p>
+             * LE range [-127..20] with 0 inside the Golden Receive Power Range
+             * and 127 as "not available" value (core spec).
+             * </p>
+             * <pre>
+             * pathloss = Tx Power Level – RSSI
+             * </pre>
+             * @see #getTxPower()
+             */
             int8_t getRSSI() const noexcept { return rssi; }
 
-            /** Return Tx Power of device as recognized at discovery and connect. */
+            /**
+             * Return Tx Power Level in dBm with ±6 dB accuracy of device as recognized at discovery and connect.
+             * <p>
+             * Core Specification Supplement, Part A, Section 1.5.
+             * </p>
+             * <p>
+             * Range [-127..20] with 127 as "not available" value (core spec).
+             * </p>
+             * <pre>
+             * pathloss = Tx Power Level – RSSI
+             * </pre>
+             * @see #getRSSI()
+             */
             int8_t getTxPower() const noexcept { return tx_power; }
 
             /**
-- 
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