Fixes (minor?) issues with the ZigBee sample

1. zigbee_configure_sleepy_behavior must be called before zigbee_enable - [source
docs](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/nrf/libraries/zigbee/zigbee_app_utils.html#c.zigbee_configure_sleepy_behavior)

2. zb_zdo_pim_set_long_poll_interval must be called after the network is joined - [source docs](https://developer.nordicsemi.com/nRF_Connect_SDK/doc/zboss/3.5.2.0/group__zdo__poll__control.html#ga3aae8929b30e71c872f937771b89c768).
On top of that, the argument for the call was incorrect - it expects ms directly.

3. Removed the unecessary CONFIG_PM, seems like there's no impact in power consumption. Could it cause some weirdness?

4. Implemented CONFIG_PRST_ZB_FACTORY_RESET_DISABLED=y to fully disable factory resetting. May aid debugging.

5. Implemented multi/single channel support. Helps with battery life when scanning networks

code/nrf-connect/samples/zigbee/Kconfig

@@ -7,7 +7,7 @@ config PRST_ZB_SLEEP_DURATION_SEC
 
 config PRST_ZB_PARENT_POLL_INTERVAL_SEC
 	int "Interval for when b-parasite polls its parent for data in seconds."
-	default 60
+	default 10
 
 config PRST_ZB_BUILD_DATE
   string "Zigbee basic cluster build date attribute. Max 16 bytes."

code/nrf-connect/samples/zigbee/prj.conf

@@ -8,9 +8,6 @@ CONFIG_GPIO=y
 CONFIG_USE_SEGGER_RTT=y
 CONFIG_SEGGER_RTT_BUFFER_SIZE_UP=4096
 
-CONFIG_PM=y
-CONFIG_PM_DEVICE=y
-
 CONFIG_NEWLIB_LIBC=y
 CONFIG_NEWLIB_LIBC_FLOAT_PRINTF=y
 
@@ -39,8 +36,17 @@ CONFIG_NET_IPV6_RA_RDNSS=n
 CONFIG_NET_IP_ADDR_CHECK=n
 CONFIG_NET_UDP=n
 
+##
+## ZigBee Channel Selection
+##
 # Get Zigbee to scan every channel.
 CONFIG_ZIGBEE_CHANNEL_SELECTION_MODE_MULTI=y
+# By default only scans channel 11 (ZigBee2MQTT default) and 15 (ZHA default).
+# Comment to scan all channels - this will make pairing consume more energy.
+# CONFIG_ZIGBEE_CHANNEL_MASK=0x8800
+
+# Uncomment to set a specific channel - this will make pairing more energy efficient.
+# CONFIG_ZIGBEE_CHANNEL=11
 
 # Enable API for powering down unused RAM parts.
 # https://developer.nordicsemi.com/nRF_Connect_SDK/doc/1.7.1/nrf/ug_zigbee_configuring.html#power-saving-during-sleep
@@ -60,4 +66,3 @@ CONFIG_FILE_SYSTEM_LITTLEFS=y
 # Factory reset method selection. Only hardware revision 2.0.0+ has button SW1. Earlier
 # revisions must select a different method. See Kconfig for options.
 # CONFIG_PRST_ZB_FACTORY_RESET_VIA_SW1=y
-CONFIG_PRST_ZB_FACTORY_RESET_DISABLED=y

code/nrf-connect/samples/zigbee/src/main.c

@@ -138,6 +138,8 @@ void zboss_signal_handler(zb_bufid_t bufid) {
         k_timer_stop(&led_flashing_timer);
         prst_restart_watchdog_stop();
         prst_led_off();
+        // Update the long polling parent interval - needs to be done after joining.
+        zb_zdo_pim_set_long_poll_interval(1000 * CONFIG_PRST_ZB_PARENT_POLL_INTERVAL_SEC);
       } else {
         LOG_DBG("Steering failed. Status: %d", status);
         prst_debug_counters_increment("steering_failure");
@@ -244,7 +246,7 @@ void update_sensors_cb(zb_uint8_t arg) {
 }
 
 void log_counter(const char *counter_name, prst_debug_counter_t value) {
-  LOG_INF("- %s: %d", counter_name, value);
+  LOG_DBG("- %s: %d", counter_name, value);
 }
 
 int main(void) {
@@ -254,9 +256,12 @@ int main(void) {
   RET_IF_ERR(prst_flash_fs_init());
   RET_IF_ERR(prst_debug_counters_init());
 
+  // Initialize sensors - quickly put them into low power mode.
+  RET_IF_ERR(prst_sensors_read_all(&sensors));
+
   prst_debug_counters_increment("boot");
 
-  LOG_INF("Dumping debug counters:");
+  LOG_DBG("Dumping debug counters:");
   prst_debug_counters_get_all(log_counter);
 
   RET_IF_ERR(prst_zb_factory_reset_check());
@@ -265,19 +270,17 @@ int main(void) {
 
   ZB_AF_REGISTER_DEVICE_CTX(&app_template_ctx);
 
+  // Kick-off the recurring task to read sensors and update ZigBee clusters.
   update_sensors_cb(/*arg=*/0);
 
-  zb_zdo_pim_set_long_poll_interval(
-      ZB_TIME_ONE_SECOND * CONFIG_PRST_ZB_PARENT_POLL_INTERVAL_SEC);
-  power_down_unused_ram();
-
   RET_IF_ERR(prst_led_flash(2));
   k_msleep(100);
 
   ZB_AF_SET_IDENTIFY_NOTIFICATION_HANDLER(PRST_ZIGBEE_ENDPOINT, identify_cb);
 
-  zigbee_enable();
   zigbee_configure_sleepy_behavior(/*enable=*/true);
+  power_down_unused_ram();
+  zigbee_enable();
 
   prst_debug_counters_increment("main_finish");
 

code/nrf-connect/samples/zigbee/src/restart_handler.c

@@ -11,7 +11,7 @@ LOG_MODULE_REGISTER(restart_handler, CONFIG_LOG_DEFAULT_LEVEL);
 void callback_work_handler(struct k_work *work) {
   LOG_INF("Running restart callback_work_handler.");
   prst_debug_counters_increment("steering_watchdog_restart");
-  zb_reset(0);
+  user_input_indicate();
 }
 
 K_WORK_DEFINE(callback_work, callback_work_handler);