OpenNuvoton N76E003-BSP adopted for Small Device C Compiler (SDCC) with some defines to make Visual Studio Code happy
BSP itself compressed into a couple of bsp/N76E003.h and bsp/N76E003.c files with multiple auxiliary APIs/drivers located in the bsp and lib folders.
Originally BSP was developed with SDCC version 3.8.0 but should work fine with any more recent versions as well (tested with SDCC versions up to 4.2.0).
Repository structure:
├── .vscode : some Visual Code settings and common tasks
│ └── tasks.json: defines the following tasks:
│ ├── build: build in the current folder
│ ├── clean: make clean in the current folder
│ ├── re-build: make clean; make; in the current folder
│ ├── erase device: erase all memory types and configuration bytes
│ └── flash device: flash the image from the current folder
├── bsp : common system files
│ ├── N76E003.c/h: main definitions for N76E003
│ ├── adc.c/h: ADC APIs
│ ├── event.c/h: simple ring buffer for generating events from ISRs
│ ├── i2c.c/h: I2C bus APIs
│ ├── iap*.c/h: In Application Programming routines to read/write MCU flash memory
│ ├── irq.c/h: interrupts handling APIs
│ ├── key.c/h: simple driver for keys (push buttons) connected to pull-up pins
│ ├── key.svg: diagram of keys handling and events generation
│ ├── pinterrupt.c/h: pin interrupt handling APIs
│ ├── pwm.c/h: PWM handling APIs
│ ├── terminal.c/h: serial communication APIs enough to support simple CLI with one line history
│ ├── tick.c/h: wake-up timer (WKT) interrupt to provide milliseconds tick events
│ ├── uart.c/h: UART 0/1 APIs.
│ └── vdd.c: ADC bandgap for calculating Vdd value
├── lib : library of common drivers
│ ├── bv4618.c/h: BV4618 LCD controller driver
│ ├── dht.c/h: DHT/AM2302 relative humidity/temperature driver
│ ├── ds3231.c/h: DS3231 Real Time Clock driver
│ ├── dump.c/h: simple pretty printer for memory dumps
│ ├── ht1621.c/h: Holtek HT1621 RAM Mapping 32x4 LCD Controller driver
│ ├── i2c_mem.c/h: I2C EEPROM 24C* driver
│ ├── lcd_lpwm.c/h: driver for LCD used to XY-LPWM and clone boards
│ ├── pcf8574.c/h: I2C I/O Extender PCF8574 driver
│ ├── pwm_range.c/h: helper functions to specify PWM frequency ranges
│ └── srfs.c: read any SFR register by its address
├── pys : python scripts
│ └── size-mcs51.py: .mem file parser for mcs51 target generated by sdcc linker
├── xsamples
│ ├── bsp-pwm: testing PWM capabilities of N76E003
│ ├── bsp-pwm-asymmetric: PWM signals generated by PWM interrupt handler
│ ├── bsp-spi: test different SPI configuration options
│ ├── bsp-template: template project for the BSP
│ ├── bsp-test: testing environment for bsp/lib
│ ├── hpdl-1414: HPDL-1414 Alphanumeric display example
│ ├── pwm-low-power: PWM to drive LED depending on Li-ion battery voltage,
│ │ power-down mode example
│ ├── xy-lpwm-fw: alternative firmware for XY-LPWM and clones
│ └── xy-lpwm-lcd: XY-LPWM LCD screen controlled by commands over serial port
└── readme.md: this file
bsp-pwm provides examples of PWM configurations and PWM interrupt processing, including phased PWM implemented using SW interrupt processing.
bsp-pwm-asymmetric provides examples of PWM signals generated by PWM interrupt processing, including inphase and antiphase signals.
bsp-spi test some of SPI configuration options and use of SPSR::TXBUF flag.
bsp-template provides skeleton example for the BSP.
bsp-test provides examples of connecting different sensors/devices to N76E003 development board:
- DHT22 (AM2302) humidity/temperature sensor
- RTC DS3231 with I2C EEPROM Atmel 24C32 on board
- 20x4 LCD with BV4618 as I2C controller
- 16x4 LCD with PCF8574 as I2C controller
- PS/2 Mini Keyboard UK Layout
- HT16K33 based quad alphanumeric display
hpdl-1414 HPDL-1414 Alphanumeric display controlled using MCP23017 I2C 16-Bit I/O Expander xy-lpwm-fw and xy-lpwm-lcd examples use popular XY-LPWM single channel PWM generator as a development board for N76E003.
XY-LPWM3 with 3 PWM channels would be even better dev board as it provides 8 keys instead or 4 and 3 PWM outputs instead of 1, example with XY-LPWM3 TDB.
BSP implements a simple Even Driven Architecture (EDA) where events are generated by interrupts procedures and then processed in the main loop. By default two interrupts are handled and generates events: UART and Timer:
...
/**
* generate EVT_TIMER every 250 msec, 4 times per second
* set to 253 instead of 250 in case if 16.6MHz is used as Fsys
* */
tick_init(250);
EA = 1; /* enable all interrupts to start tick timer */
...
/* events processing loop */
while (1) {
evt.evt = event_get();
if (evt.type) {
if (evt.type == EVT_UART_RX) {
cli_interact(evt.data);
continue;
}
if (evt.type == EVT_TICK) {
tick++;
/**
* we have 4 tick events per second, so
* count to 4 before calling our timer handler
* */
if (tick >= 4) {
timer();
tick = 0;
}
continue;
}
}
}See event.h and event.c for more details.
To compile any of the examples make sure that you have make (make from avr-gcc works just fine), sdcc and Nuvoton's ICP nulink in the path. If not, modify corresponding defines in the makefiles.
You also will need Python 3.x installed for size-mcs51.py to work.
This script parses .mem file generated by SDCC linker and list information about memory sections:
> size-mcs51.py main.mem
Name Start End Size Max Spare
---------------- ------ ------ ----- ----- -----------
REG BANKS 0x0000 0x000F 2 4 2
IDATA 0x0000 0x008B 140 256 116
OVERLAYS 3
STACK 0x008C 0x00FF 116 248 116
EXTERNAL RAM 0x0001 0x00e6 230 768 538 70.1% free
ROM/EPROM/FLASH 0x0000 0x36b7 14008 18432 4424 24.0% free
Visual Studio Code IntelliSence configuration expects SDCCPATH environment variable to point to SDCC installation folder (needed to access SDCC header files).
There are a few different Nuvoton N76E003 development boards available online.
This one was used for the BSP examples:
Minimal configuration uses programmer pins and UART (38400 baud rate):
G R C D V + 3 T R G
N S L A D 5 V X X N
D T K T D V 3 0 0 D
| | | | | | | | | |
+----------------------+
---|11 P1.4 VDD 9 |--- VDD
---|12 P1.3 GND 7 |--- GND
---|13 P1.2 P1.5 10|---
---|14 P1.1 P1.6 8 |--- DAT [ICP]
---|15 P1.0 P1.7 7 |---
---|16 P0.0 P3.0 5 |---
---|17 P0.1 P2.0 2 |--- RST [ICP]
[ICP] CLK ---|18 P0.2 P0.7 3 |--- UART0 RX
---|19 P0.3 P0.6 2 |--- UART0 TX
---|20 P0.4 P0.5 1 |---
+----------------------+
leaving 13 IO pins available.
This one was used for the pwm-low-power example:
G V R T
N D X X
D D 0 0
| | | |
+---------------------+
---|11 P1.4 P1.5 11|--- (BLINK)
---|12 P1.3 VDD 10|--- VDD
---|13 P1.2 VIN 9 |--- VIN
---|14 P1.1 GND 8 |--- GND
---|15 P1.0 P1.7 7 |---
---|16 P0.0 P3.0 5 |---
---|17 P0.1 P2.0 2 |--- RST [ICP]
[ICP] CLK ---|18 P0.2 P0.7 3 |--- UART0 RX
---|19 P0.3 P0.6 2 |--- UART0 TX
---|20 P0.4 P0.5 1 |---
+---------------------+
| | | | |
G R C D V
N S L A D
D T K T D
Note that this board does not have P1.6 (DAT [ICP]) exposed on the side pins.
Pin P1.5 has on-board blink LED connected.
7133-1 voltage regulator (24V to 3.3V):
M5333B voltage regulator (35V to 3.3V):
Three channel board:
Nuvoton N76E003 official site https://www.nuvoton.com/products/microcontrollers/8bit-8051-mcus/low-pin-count-8051-series/n76e003/
NuMicro software development tools https://github.com/OpenNuvoton/Nuvoton_Tools
OpenNuvoton N76E003 BSP https://github.com/OpenNuvoton/N76E003-BSP
Small Device C Compiler http://sdcc.sourceforge.net/