arch/arm/src/max326xx: Fixes UART interrupt problems. With these changes, the NSH configuration appears stable and is no longer conditioned on EXPERIMENTAL.

arch/arm/Kconfig

@@ -187,7 +187,6 @@ config ARCH_CHIP_LPC54XX
 config ARCH_CHIP_MAX326XX
 	bool "Maxim Integrated MAX326XX"
 	select ARCH_HAVE_FETCHADD
-	depends on EXPERIMENTAL
 	---help---
 		Maxim Integrated MAX326XX microcontrollers (ARM Cortex-M4F).
 

arch/arm/src/max326xx/Kconfig

@@ -15,18 +15,22 @@ choice
 config ARCH_CHIP_MAX32620
 	bool "MAX32620"
 	select ARCH_FAMILY_MAX32620
+	depends on EXPERIMENTAL  # Not fully implemented
 
 config ARCH_CHIP_MAX32621
 	bool "MAX32621"
 	select ARCH_FAMILY_MAX32620
+	depends on EXPERIMENTAL  # Not fully implemented
 
 config ARCH_CHIP_MAX32630
 	bool "MAX32630"
 	select ARCH_FAMILY_MAX32630
+	depends on EXPERIMENTAL  # Not fully implemented
 
 config ARCH_CHIP_MAX32632
 	bool "MAX32632"
 	select ARCH_FAMILY_MAX32630
+	depends on EXPERIMENTAL  # Not fully implemented
 
 config ARCH_CHIP_MAX32660
 	bool "MAX32660"

arch/arm/src/max326xx/max32660/max32660_serial.c

@@ -121,7 +121,7 @@
 
 /* UART events */
 
-#define UART_INT_TX            UART_INT_TXFIFOLVL
+#define UART_INT_TX            (UART_INT_TXFIFOLVL | UART_INT_TXFIFOAE)
 #define UART_INT_RX            (UART_INT_RXFIFOLVL | UART_INT_RXTO)
 #define UART_INT_RXERRORS      (UART_INT_FRAME | UART_INT_PARITY | \
                                 UART_INT_RXOVR)
@@ -534,7 +534,7 @@ static int max326_interrupt(int irq, void *context, FAR void *arg)
 
       /* Clear pending interrupt flags */
 
-      max326_serialout(priv, MAX326_UART_STAT_OFFSET,
+      max326_serialout(priv, MAX326_UART_INTFL_OFFSET,
                        intfl & UART_INT_ALL);
 
       /* Handle incoming, receive bytes.

configs/max32660-evsys/README.txt

@@ -44,24 +44,15 @@ Status
     progress.  Added a run-from-SRAM configuration to keep from locking
     up the board on bad configurations.  The rest of the bring-up will
     use this SRAM configuration.
-
-    Some success the end of the day:
-
-      ACFH
-
-      NuttShell (NSH) NuttX-7.27
-      nsh>
-
-    Still lots to do though.  There is TX interrupt problem so it doesn't
-    look this good in real life.  Probably due to TX FIFO level interrupt
-    issues.  I comes up with 'NuttShell'  then stops.  I hit enter and
-    " (NSH) NuttX" comes out etc.  So it looks like Rx input is driving
-    the Tx output.
+    The NSH prompt comes up, but there is some interrupt-related problem
+    that makes the console unusable.
   2018-11-28:  Found that the WFI instruction in the IDLE loop was causing
     instability.  System ran OK until it was in IDLE then it became
-    unstable.  Commenting out the WIF restores stability.  The port does
-    now run safely from FLASH although with some missing UART interrupts.
+    unstable.  Commenting out the WIF restores stability.  The port now
+    runs safely from FLASH although still with missing UART interrupts.
     Also fixed the on-board LED which now currently reflects the state.
+  2018-11-29:  Resolved the UART interrupt issue.  The NSH configuration
+    now appears fully functional.  Removed EXPERIMENTAL from configuration.
 
 Serial Console
 ==============

configs/max32660-evsys/nsh/defconfig

@@ -13,8 +13,8 @@ CONFIG_ARMV7M_USEBASEPRI=y
 CONFIG_BOARD_LOOPSPERMSEC=8192
 CONFIG_BUILTIN=y
 CONFIG_DISABLE_POLL=y
-CONFIG_EXPERIMENTAL=y
 CONFIG_FS_PROCFS=y
+CONFIG_INTELHEX_BINARY=y
 CONFIG_MAX326XX_UART1=y
 CONFIG_MAX_TASKS=16
 CONFIG_MAX_WDOGPARMS=2