Clock io (input, output, how to configure)
IODigital and analog resources can be passed through 25 I/O pins (C805 1f3 2 0), each port pin can be defined as
1
General Purpose I/O (GPIO) or 0 analog inputsAll port I/O are resistant to 5V voltage port I/O unit can be configured to
Open drain or push-pull mode, port output mode register Pnmdout set, n = 0,1, 2, 3p1mdout |= 0x0f;//0000 1111
the 0-3 port of the P1 is 1.That is, push-pull output mode p2mdout |= 0x0c;//0000 1100 corresponding P2.2, P2.3 push-pull output
registers XBR0 and XBR1 are used to allocate physical I/O pins for digital I/O resources
Pnmdin Select the input mode (analog or digital) for all port pins
Note: For ports P0, P1, and P2.0 ~ P2.3 working on standard port I/O input/output mode, cross switch required
Must be enabled. When the crossover switch is disabled, the port output driver is disabled. P2.4 ~ P2.7 and P3.0 are always standard
GPIO Use
XBR1 |= (1<<6);
USB Clock
C8051F 320/1 has a
programmable Internal oscillator, an external oscillator drive circuit, and a 4 times-fold clock multiplier。
The OSCICN and OSCICL registers can be programmed to enable/disable the internal oscillator and adjust its output frequency (
As shown in 13.1). The system clock (SYSCLK) can come from an internal oscillator, an external oscillator circuit, or a 4 times-fold clock multiplier
Two frequency. The USB clock (USBCLK) can come from an internal oscillator, an external oscillator circuit, or a 4 times-fold clock multiplier.
Table 13.3 shows the electrical characteristics of the internal oscillator
once the frequency of the internal oscillator is modified, it can no longer be used as a USB clockThe 4 times-fold clock multiplier allows the 48MHz clock required to generate full-speed USB communication using a 4 times-M Hz oscillator with the CLKMUL register configured with a clock multiplier of the time-of-use. The steps to configure and enable the 4 times-fold clock multiplier are as follows:
1. Resets the clock multiplier by writing 0x00 to the Register Clkmul.
2. Select the input of the clock multiplier with the Mulsel bit.
3. Mulen-bit Enable clock multiplier (clkm UL | = 0x80).
4. Delay is greater than 5µs.
5. Initialize the clock multiplier with the Mulinit bit (Clkmul | = 0 x C 0).
6. Query Waiting Mulrdy = ' 1 '. It's all the same. Multiply register configuration void clock_init (void)
{
int8u i;
if ((Clkmul & (1<<5))) return;//If the multiplication register is locked, return
Clkmul = 0;
Clkmul |= (1<<7);//clock multiplier enable bit
for (i = 0; i <; i + +);//delay
Clkmul |= 0xc0;//1100 0000, initialize clock multiplier
for (i = 0; i <; i + +);
while (!) ( Clkmul & (1<<5));//Clock multiplier stable, Mulrdy readout value is ' 1 '
Clksel = (2<<0);
}
Serial Port
void Port_init (void)
{
XBR1 = 0x40; Enable Crossbar and Weak pullups
XBR0 = 0x01;
P0mdout |= 0x10; Set TX pin to Push-pull
} void Uart0_init (void)
{
SCON0 = 0x10; 0x0001 0000The logic level of the 8-bit UART no stop bit is ignored UART0 receive allowsScon0:8-bit variable bit rate
Level of STOP bit is ignored
//
RX enabled
Ninth Bits is zeros
Clear RI0 and TI0 bits//configuration
t1m,
sca1:0if (sysclk/baudrate/2/256 < 1) {
TH1 =-(SYSCLK/BAUDRATE/2);
Ckcon |= 0x08; //
t1m = 1; sca1:0= XX
} else if (sysclk/baudrate/2/256 < 4) {
TH1 =-(SYSCLK/BAUDRATE/2/4);
Ckcon &= ~0x0b; t1m = 0; sca1:0 = 01
Ckcon |= 0x01;
} else if (sysclk/baudrate/2/256 < 12) {
TH1 =-(SYSCLK/BAUDRATE/2/12);
Ckcon &= ~0x0b; t1m = 0; sca1:0 = 00
} else if (sysclk/baudrate/2/256 < 48) {
TH1 =-(SYSCLK/BAUDRATE/2/48);
Ckcon &= ~0x0b; t1m = 0; sca1:0 = 10
Ckcon |= 0x02;
} else {
while (1); Error. Unsupported baud rate
}
TL1 = TH1; Init Timer1
Tmod &= ~0xf0; Tmod:timer 1 in 8-bit autoreload
Tmod |= 0x20;
TR1 = 1; START Timer1
TI0 = 1; Indicate TX0 ready
}
ADCConfigure with configurator: ADC0CN = 0x02; ADC0 disabled, normal tracking,
Conversion triggered on TMR2 overflow ADC0
Trigger with clockEIE1 |= 0x08; Enable ADC0 conversion complete int.
Interrupt ConfigurationIn Adcmux set there choose P2.4, and GND.
PIN Configurationamx0p = 0x0C; ADC0 positive input = P2.4
amx0n = 0x1F; ADC0 Negative input = GND
i.e., single ended modeP2mdin = 0xef;//p2.4 is set to analog input, Portinit also the serial port configuration and Clock 2
I²cvoid Smbus_init (void);
void Smbus_isr (void);
C8051F320 Learning, single-chip microcomputer is not only clock, IO, serial, USB and other peripheral usage
