Update XTAL32M settings to the robust settings as recommended in the HW guidelines

ID: LPCBARESDK-859

Status: Fixed

First reported: 6.0.18.1182.1

Fixed in: 6.0.20.1338

Description

The default XTAL32M oscillator settings in the SDK6.0.18.1182.1 or earlier might lead in some cases to an interruption of oscillation

Workaround

Customers working with an earlier SDK version should change the current and amplitude settings of the XTAL32M. This fix will be included in the next release and we will introduce an improved current and amplitude setting for the XTAL32M oscillator.

XTAL32M_CTRL0_REG: CORE_CUR_SET = 1
XTAL32M_CTRL0_REG: CORE_AMPL_TRIM = 5

To achieve this, the SDK must be adapted in:

• Location: sdk/platform/arch/main

• Filename: arch_system.c

• API name: system_init()

--- arch_system.c       2022-12-01 15:20:54.739927400 +0100
+++ arch_system.c       2022-11-23 18:05:32.000000000 +0100
@@ -1268,8 +1268,7 @@
     // Configure XTAL32M
     SetBits16(TRIM_CTRL_REG, XTAL_TRIM_SELECT, 2);       // only CLK_FREQ_TRIM_REG will be used for XTAL32M trimming
     SetBits16(XTAL32M_START_REG, XTAL32M_START, 0);
+    SetBits16(XTAL32M_CTRL0_REG, CORE_CUR_SET, 1);
+    SetBits16(XTAL32M_CTRL0_REG, CORE_AMPL_TRIM, 5);
-    SetBits16(XTAL32M_CTRL0_REG, CORE_CUR_SET, 2);
 #else
     // Confirm XTAL16M calibration
     xtal16m_calibration_check();

And

• Location: sdk/platform/arch/main

• Filename: arch_hibernation.c

• API name: arch_hibernation_restore()

@@ -335,8 +335,7 @@
     // Configure XTAL32M
     SetBits16(TRIM_CTRL_REG, XTAL_TRIM_SELECT, 2);  // only CLK_FREQ_TRIM_REG will be used for XTAL32M trimming
     SetBits16(XTAL32M_START_REG, XTAL32M_START, 0);
+    SetBits16(XTAL32M_CTRL0_REG, CORE_CUR_SET, 1);
+    SetBits16(XTAL32M_CTRL0_REG, CORE_AMPL_TRIM, 5);
-    SetBits16(XTAL32M_CTRL0_REG, CORE_CUR_SET, 2);

     if ((clk_ctrl_reg_backup & RUNNING_AT_XTAL32M) == RUNNING_AT_XTAL32M)
     {

Additionally, make sure not to set the CLK_FREQ_TRIM_REG to 0x0 before going to sleep in:

• Location: sdk/platform/arch/main

• Filename: arch_main.c

• API name: arch_switch_clock_goto_sleep()

delete

@@ -340,6 +340,9 @@
 #else
     while( (GetWord16(CLK_CTRL_REG) & RUNNING_AT_RC16M) == 0 );
 #endif
-    SetWord16(CLK_FREQ_TRIM_REG, 0);                        // Set zero value to CLK_FREQ_TRIM_REG
-    // Do not disable the XTAL16M (DA14585/586) or XTAL32M (DA14531).
-    // It will be disabled when we sleep...
 #endif // (USE_POWER_OPTIMIZATIONS)
     }
 }

Reference

Refer to the section 3.2.2.2 in AN-B-075 : DA14531/530 Hardware Guidelines