From cd60e9af4d22ba8aed1dad6c543d1bd70f0bbc28 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20J=C3=A4ger?= <martin@libre.solar>
Date: Thu, 20 May 2021 14:24:23 +0200
Subject: [PATCH] ISL94202: Avoid balancing during measurements

Fixes #16
---
 src/isl94202/bms_isl94202.c | 25 +++++++++++++++++++++++++
 src/isl94202/registers.h    |  6 +++---
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/isl94202/bms_isl94202.c b/src/isl94202/bms_isl94202.c
index f11abfc..474b951 100644
--- a/src/isl94202/bms_isl94202.c
+++ b/src/isl94202/bms_isl94202.c
@@ -118,6 +118,31 @@ bool bms_dis_switch(BmsConfig *conf, BmsStatus *status, bool enable)
 
 void bms_apply_balancing(BmsConfig *conf, BmsStatus *status)
 {
+    uint8_t stat3;
+    isl94202_read_bytes(ISL94202_STAT3, &stat3, 1);
+
+    /*
+     * System scans for voltage, current and temperature measurements happen in different
+     * intervals depending on the mode. Cell balancing should be off during voltage scans.
+     *
+     * Each scan takes max. 1.7 ms. Choosing 16 ms off-time for voltages to settle.
+     */
+    if (stat3 & ISL94202_STAT3_INIDLE_Msk) {
+        // IDLE mode: Scan every 256 ms
+        isl94202_write_delay(ISL94202_CBONT, ISL94202_DELAY_MS, 240, 0);
+        isl94202_write_delay(ISL94202_CBOFFT, ISL94202_DELAY_MS, 16, 0);
+    }
+    else if (stat3 & ISL94202_STAT3_INDOZE_Msk) {
+        // DOZE mode: Scan every 512 ms
+        isl94202_write_delay(ISL94202_CBONT, ISL94202_DELAY_MS, 496, 0);
+        isl94202_write_delay(ISL94202_CBOFFT, ISL94202_DELAY_MS, 16, 0);
+    }
+    else if (!(stat3 & ISL94202_STAT3_INSLEEP_Msk)) {
+        // NORMAL mode: Scan every 32 ms
+        isl94202_write_delay(ISL94202_CBONT, ISL94202_DELAY_MS, 16, 0);
+        isl94202_write_delay(ISL94202_CBOFFT, ISL94202_DELAY_MS, 16, 0);
+    }
+
     /*
      * Balancing is done automatically, just reading status here (even though the datasheet
      * tells that the CBFC register value cannot be used for indication if a cell is
diff --git a/src/isl94202/registers.h b/src/isl94202/registers.h
index cda1491..c51bbc3 100644
--- a/src/isl94202/registers.h
+++ b/src/isl94202/registers.h
@@ -116,9 +116,9 @@
 #define ISL94202_CBONT_Msk  (0xFFFU << ISL94202_CBON_Pos)
 
 // Cell Balance Off Time (CBOFF)
-#define ISL94202_CBOFT      (0x26U)
-#define ISL94202_CBOFT_Pos  (0x0U)
-#define ISL94202_CBOFT_Msk  (0xFFFU << ISL94202_CBOF_Pos)
+#define ISL94202_CBOFFT     (0x26U)
+#define ISL94202_CBOFFT_Pos (0x0U)
+#define ISL94202_CBOFFT_Msk (0xFFFU << ISL94202_CBOF_Pos)
 
 // Cell Balance Minimum Temperature Limit (CBUTS)
 #define ISL94202_CBUTS      (0x28U)