From 3c236a7d6ee75e9f920238787a2112d3c678d64a Mon Sep 17 00:00:00 2001
From: Eldon Stegall <periphgithub@eldondev.com>
Date: Mon, 14 Nov 2022 14:42:25 -0500
Subject: [PATCH] ina219: Interpret signed output register values

The current and shunt voltage register values are signed, twos
complement format. In my tests interpreting them directly in the
way implemented here gave output consistent with other ina219
libraries.
---
 ina219/ina219.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/ina219/ina219.go b/ina219/ina219.go
index 0226ba1..c327c55 100644
--- a/ina219/ina219.go
+++ b/ina219/ina219.go
@@ -5,6 +5,7 @@
 package ina219
 
 import (
+	"unsafe"
 	"encoding/binary"
 	"errors"
 	"fmt"
@@ -110,7 +111,7 @@ func (d *Dev) Sense() (PowerMonitor, error) {
 		return PowerMonitor{}, errReadShunt
 	}
 	// Least significant bit is 10µV.
-	pm.Shunt = physic.ElectricPotential(shunt) * 10 * physic.MicroVolt
+	pm.Shunt = physic.ElectricPotential(*((*int16)(unsafe.Pointer(&shunt)))) * 10 * physic.MicroVolt
 
 	bus, err := d.m.ReadUint16(busVoltageRegister)
 	if err != nil {
@@ -128,7 +129,7 @@ func (d *Dev) Sense() (PowerMonitor, error) {
 	if err != nil {
 		return PowerMonitor{}, errReadCurrent
 	}
-	pm.Current = physic.ElectricCurrent(current) * d.currentLSB
+	pm.Current = physic.ElectricCurrent(*((*int16)(unsafe.Pointer(&current)))) * d.currentLSB
 
 	power, err := d.m.ReadUint16(powerRegister)
 	if err != nil {