DM&P Serial Port DOS Library Reference

2007/11/12 Version 0.13

Serial Port Library

SerPort DOS library is from the kernel of our RSIP that supports 8 serial ports and interrupt-driven communication. It provides simple C functions and save a lot of development time for programmer. SerPort is for DM&P products with M6117D/Vortex86/Vortex86SX CPUs. It is a DOS real mode and large memory model library.

Before using SerPort library, you should know the I/O base address and IRQ of COM ports you want to use. The default IRQ of COM1/2 is IRQ4/3. If SBC has 4 COM ports, the factory default value is that COM3/4 uses the same IRQ as COM1/2.The default I/O base address and IRQ of our SBC are:

COM1	3F8H	IRQ4
COM2	2F8H	IRQ3
COM3	3E8H	IRQ4
COM4	2E8H	IRQ3

For 4 COM ports usage, we recommend user to set COM3/4 to use IRQ10/11 because SerPort does not support shared IRQ.For example, you can find a JP7 of 6026 to set COM3/4 to use IRQ10/11.The table will show you the IRQ usage SerPort supports:

COM1	COM2	COM3	COM4	Status
IRQ4	IRQ3			OK
		IRQ4	IRQ3	OK
IRQ4	IRQ3	IRQ10	IRQ11	OK
IRQ4	IRQ3	IRQ4	IRQ3	Not Supported

For 8 COM ports usage, we recommend those configurations::

COM Port	1	2	3	4	5	6	7	8
IRQ	4	3	10	11	5	6	7	15
I/O Address	3F8H	2F8H	3E8H	2E8H	338H	238H	228H	220H

P.S. Make sure the IRQ in table is not used by other PCI device. This is because SerPort does not support shared IRQ.

User can find a demo.c from SerPort library. It is a demo program that use COM1 to send key press messages and use COM2 to receive messages. You should have a crossed cable (pin2 and pin 3 is changed) before your test. Connect COM1 and COM2 on your SBC with crossed cable. Run demo.exe, any key press will send to COM1 and COM2 will receive the message. Or, you can connect COM1 of SBC(1) to COM2 of SBC(2). Both of then run demo.exe and any key press message on SBC(1) will send to SBC(2).

Function Reference

• int SerPort_Open()
• int SerPort_Close()
• int SerPort_IsOk()
• void SerPort_SetParam()
• void SerPort_Clear()
• int SerPort_IsParityError()
• unsigned int SerPort_Avail()
• int SerPort_SendBuf()
• int SerPort_SendStr()
• int SerPort_SendByte()
• int SerPort_RecvBuf()
• int SerPort_RecvByte()
• int SerPort_GetDTR()
• void SerPort_SetDTR()
• int SerPort_GetRTS()
• void SerPort_SetRTS()

SerPort_Open(COM1,4096,0x3f8,4);

int SerPort_Close(enum COM_t ComPort);

SerPort_Close(COM1);

if(SerPort_IsOk(COM1)==0) printf("Unable to initialize COM1.\n");

/* Set baud rate 115200 bps, no parity, 8 bits, 1 stop bit */SerPort_SetParam(COM1,BAUD_115200,PARITY_NO,LENGTH_8_BIT,STOPBIT_1_BIT);

SerPort_Clear(COM1);

if(SerPort_IsParityError(COM1)!=0) printf("Parity error.\n");

if(SerPort_Avail(COM1)) SerPort_RecvBuf(COM1,pcBuf,1024);

SerPort_SendBuf(COM1,pcBuf,1024);

char *szAtCmd = "ATZ";SerPort_SendStr(COM1,szAtCmd);

char c = 'x';SerPort_SendByte(COM1,c);

char szBuf[1024];SerPort(COM1,szBuf,1024);

char c;SerPort_RecvByte(COM1,&c);

int SerPort_GetDTR(enum COM_t ComPort);

if(SerPort_GetDTR(COM1)){/* do something */}

void SerPort_SetDTR(enum COM_t ComPort,int n);

SerPort_SetDTR(COM1,1);

int SerPort_GetRTS(enum COM_t ComPort);

if(SerPort_GetRTS(COM1)){/* do something */}

void SerPort_SetRTS(enum COM_t ComPort,int n);

SerPort_SetRTS(COM1,1);