parent
bd6ee3a06d
commit
f02b2a4fdd
1 changed files with 1 additions and 123 deletions
@ -1,123 +1 @@ |
|||||||
${ProjName}: |
# Bibliothèque pour associer un écran e-paper à un LPC804 |
||||||
UART0_Terminal |
|
||||||
|
|
||||||
|
|
||||||
Intended purpose: |
|
||||||
To demonstrate the configuration and use of the USART module, in asynchronous |
|
||||||
mode, while communicating with a terminal emulator. |
|
||||||
|
|
||||||
|
|
||||||
Functional description: |
|
||||||
* In this example UART0 communicates with a terminal emulator running on the PC, via a |
|
||||||
USB-to-RS232 breakout cable or via the NXP LPC11Uxx VCOM serial port. |
|
||||||
* The user is prompted to enter a string (not to exceed 32 characters), terminated by [Enter]. |
|
||||||
* Each character that is entered is echoed back to the terminal by the UART0 |
|
||||||
ISR, and the characters are stored in an array for future use. |
|
||||||
* When the user types [Enter], a NUL character is appended to the array, and |
|
||||||
a handshake flag is set by the ISR for the main routine. |
|
||||||
* Upon seeing the handshake flag, the main routine prints the stored string to |
|
||||||
the terminal, and the process repeats. |
|
||||||
|
|
||||||
|
|
||||||
External connections: |
|
||||||
* To use the NXP LPC11Uxx VCOM Serial Port: |
|
||||||
1. No external connections are necessary. |
|
||||||
2. The Max board must have the necessary solder-bump jumper modifications: |
|
||||||
A. For LPC812 Max board, short pins 1 and 2 of both SJ1 and SJ4 |
|
||||||
B. For LPC824 Max board, short pins 2 and 3 of SJ9 |
|
||||||
C. For LPC845 Max board, no modification is needed. |
|
||||||
C. For LPC802 LPCXpresso board, no modification is needed. |
|
||||||
C. For LPC804 LPCXpresso board, no modification is needed. |
|
||||||
3. The terminal emulator can then be connected to the NXP LPC11Uxx VCOM serial port which |
|
||||||
enumerates when the board is connected. It appears something like this: |
|
||||||
COM13: NXP LPC11Uxx VCOM serial port (COM13) |
|
||||||
|
|
||||||
* To use a USB-to-RS232 breakout cable: |
|
||||||
1. There are three external connections necessary: RXD and TXD based on the SWM |
|
||||||
settings, plus a ground connection. The RXD and TXD pins can be chosen in chip_setup.h. |
|
||||||
The defaults are as follows: |
|
||||||
P0.25 = U0_TXD = breakout cable RXD |
|
||||||
P0.24 = U0_RXD = breakout cable TXD |
|
||||||
Board GND = breakout cable GND |
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
Notes on the baud rate and FRG: |
|
||||||
* The BRG and FRG settings are calculated in two steps, as follows: |
|
||||||
// For asynchronous mode (UART mode) the formula is: |
|
||||||
// (BRG + 1) * (1 + (m/256)) * (16 * baudrate Hz.) = FRG_in Hz. |
|
||||||
// We proceed in 2 steps. |
|
||||||
// Step 1: Let m = 0, and round (down) to the nearest integer value of BRG for the desired baudrate. |
|
||||||
// Step 2: Plug in the BRG from step 1, and find the nearest integer value of m, (for the FRG fractional part). |
|
||||||
// |
|
||||||
// Step 1 (with m = 0) |
|
||||||
// BRG = ((FRG_in Hz.) / (16 * baudrate Hz.)) - 1 |
|
||||||
// = (30,000,000/(16 * 9600)) - 1 |
|
||||||
// = 194.3 |
|
||||||
// = 194 (rounded) |
|
||||||
// |
|
||||||
// Step 2. |
|
||||||
// m = 256 * [-1 + {(FRG_in Hz.) / (16 * baudrate Hz.)(BRG + 1)}] |
|
||||||
// = 256 * [-1 + {(30,000,000) / (16*9600)(195)}] |
|
||||||
// = 0.002 |
|
||||||
// = 0 (rounded) |
|
||||||
|
|
||||||
|
|
||||||
Program Flow: |
|
||||||
* This example runs with: |
|
||||||
system_ahb_clk = 15 MHz. (main_clk = 15 MHz. FRO direct output) |
|
||||||
UART0CLK = 15 MHz. (FRG0CLKSEL = main_clk, FCLKSEL0 = frg0clk) |
|
||||||
See chip_setup.h and SystemInit() |
|
||||||
|
|
||||||
* main() routine |
|
||||||
1. Clocks to USART0 and the SWM are enabled. |
|
||||||
|
|
||||||
2. The SWM is configured as per above. |
|
||||||
|
|
||||||
3. The UARTCLKDIV and the FRG (both in SYSCON) are configured as per above |
|
||||||
(for 9600 b.p.s.). |
|
||||||
|
|
||||||
4. USART0 is given a peripheral reset. |
|
||||||
|
|
||||||
5. USART0 BRG is configured as per above (for 9600 b.p.s.). |
|
||||||
|
|
||||||
6. USART0 CFG register is configured for: |
|
||||||
8 data bits |
|
||||||
no parity |
|
||||||
one stop bit |
|
||||||
no flow control |
|
||||||
asynchronous mode |
|
||||||
no loop-back |
|
||||||
|
|
||||||
7. USART0 CTL register is configured for: |
|
||||||
no continuous break |
|
||||||
no address detect |
|
||||||
no Tx disable |
|
||||||
no CC |
|
||||||
no CLRCC |
|
||||||
|
|
||||||
8. USART0 Rx Ready interrupt is enabled, and code execution enters the main while(1) |
|
||||||
loop. |
|
||||||
|
|
||||||
9. The user is prompted to enter a string, and each character is echoed by the |
|
||||||
ISR back to the terminal until the NUL terminator is encountered. |
|
||||||
|
|
||||||
10. When the NUL terminator is encountered, the ISR sets a handshake flag for |
|
||||||
main, which prints the entire received string to the terminal, and the process repeats. |
|
||||||
|
|
||||||
|
|
||||||
This example runs from Flash. |
|
||||||
|
|
||||||
|
|
||||||
To run this code: |
|
||||||
1. Build |
|
||||||
2. Program memory, then reset target |
|
||||||
or |
|
||||||
2. Debug |
|
||||||
3. Run or Go |
|
||||||
|
|
||||||
Note: It may be necessary to power-cycle the board in order to regain control of the reset button after programming. |
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
Loading…
Reference in new issue