UA1ZBE Custom Firmware v1.0

Features:
- VFO mode with direct frequency input
- POCSAG decoder (512/1200 baud) with BCH(31,21) correction
- Full-screen Spectrum analyzer
- FM Radio receiver
- RSSI signal indicator overlay
- Custom boot splash (UA1ZBE / POCSAG pager / build date)

Architecture:
- app/mode.c — mode dispatcher (VFO/POCSAG/Spectrum/FM)
- app/boot_splash.c — 2-second boot splash
- app/pocsag/ — POCSAG decoder + BCH correction
- app/display_rssi.c — RSSI indicator
- main.c — entry point with custom init
- syscalls.c — bare-metal _sbrk stub

Build: arm-none-eabi-gcc -Os -flto -Wall -Werror -Wextra
Size: 57.9KB Flash / 3.6KB RAM

Controls:
- 0-9: Direct frequency input (VFO)
- SK2: POCSAG mode
- SK1: Spectrum analyzer
- 0: FM Radio
- EXIT: Return to VFO
- F/*: Toggle 512/1200 baud (in POCSAG)

driver/backlight.c

@@ -0,0 +1,118 @@
+/* Copyright 2023 Dual Tachyon
+ * https://github.com/DualTachyon
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *     Unless required by applicable law or agreed to in writing, software
+ *     distributed under the License is distributed on an "AS IS" BASIS,
+ *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *     See the License for the specific language governing permissions and
+ *     limitations under the License.
+ */
+
+#include "backlight.h"
+#include "bsp/dp32g030/gpio.h"
+#include "bsp/dp32g030/pwmplus.h"
+#include "bsp/dp32g030/portcon.h"
+#include "driver/gpio.h"
+#include "settings.h"
+
+// this is decremented once every 500ms
+uint16_t gBacklightCountdown_500ms = 0;
+bool backlightOn;
+
+void BACKLIGHT_InitHardware()
+{
+	// 48MHz / 94 / 1024 ~ 500Hz
+	const uint32_t PWM_FREQUENCY_HZ =  1000;
+	PWM_PLUS0_CLKSRC |= ((48000000 / 1024 / PWM_FREQUENCY_HZ) << 16);
+	PWM_PLUS0_PERIOD = 1023;
+
+	PORTCON_PORTB_SEL0 &= ~(0
+		// Back light
+		| PORTCON_PORTB_SEL0_B6_MASK
+		);
+	PORTCON_PORTB_SEL0 |= 0
+		// Back light PWM
+		| PORTCON_PORTB_SEL0_B6_BITS_PWMP0_CH0
+		;
+
+	PWM_PLUS0_GEN = 	
+		PWMPLUS_GEN_CH0_OE_BITS_ENABLE |
+		PWMPLUS_GEN_CH0_OUTINV_BITS_ENABLE |
+		0;
+
+	PWM_PLUS0_CFG =  	
+		PWMPLUS_CFG_CNT_REP_BITS_ENABLE |
+		PWMPLUS_CFG_COUNTER_EN_BITS_ENABLE |
+		0;
+}
+
+void BACKLIGHT_TurnOn(void)
+{
+	if (gEeprom.BACKLIGHT_TIME == 0) {
+		BACKLIGHT_TurnOff();
+		return;
+	}
+
+	backlightOn = true;
+	BACKLIGHT_SetBrightness(gEeprom.BACKLIGHT_MAX);
+
+	switch (gEeprom.BACKLIGHT_TIME) {
+		default:
+		case 1:	// 5 sec
+		case 2:	// 10 sec
+		case 3:	// 20 sec
+			gBacklightCountdown_500ms = 1 + (2 << (gEeprom.BACKLIGHT_TIME - 1)) * 5;
+			break;
+		case 4:	// 1 min
+		case 5:	// 2 min
+		case 6:	// 4 min
+			gBacklightCountdown_500ms = 1 + (2 << (gEeprom.BACKLIGHT_TIME - 4)) * 60;
+			break;
+		case 7:	// always on
+			gBacklightCountdown_500ms = 0;
+			break;
+	}
+}
+
+void BACKLIGHT_TurnOff()
+{
+#ifdef ENABLE_BLMIN_TMP_OFF
+	register uint8_t tmp;
+
+	if (gEeprom.BACKLIGHT_MIN_STAT == BLMIN_STAT_ON)
+		tmp = gEeprom.BACKLIGHT_MIN;
+	else
+		tmp = 0;
+
+	BACKLIGHT_SetBrightness(tmp);
+#else
+	BACKLIGHT_SetBrightness(gEeprom.BACKLIGHT_MIN);
+#endif
+	gBacklightCountdown_500ms = 0;
+	backlightOn = false;
+}
+
+bool BACKLIGHT_IsOn()
+{
+	return backlightOn;
+}
+
+static uint8_t currentBrightness;
+
+void BACKLIGHT_SetBrightness(uint8_t brigtness)
+{
+	currentBrightness = brigtness;
+	PWM_PLUS0_CH0_COMP = (1 << brigtness) - 1;
+	//PWM_PLUS0_SWLOAD = 1;
+}
+
+uint8_t BACKLIGHT_GetBrightness(void)
+{
+	return currentBrightness;
+}