在文本中，将展示如何将EPICS asyn模块和其他库联用，从而实现对arm单板机上GPIO口的控制。
在本例中使用到的硬件是：
在程序中需要厂家提供的wringPi库，才能通过C语言库函数调用实现对其GPIO的控制。
以下是这个单板机GPIO的管脚对应关系，本程序中用到的wPi编号是9和10：
本IOC应用程序，仅需要需要base和asyn模块，在configure/RELEASSE文件中指定：
SUPPORT = /usr/local/EPICS/synApps/support
ASYN = ${SUPPORT}/asyn
EPICS_BASE = /usr/local/EPICS/base
以下是cpp源代码，它继承了asynPortDriver类，并且重写了其writeUInt32Digital方法，用于在指定GPIO管脚上，设置电平状态：
# drvgpioasyn.cpp
#include <iocsh.h>
#include <epicsThread.h>
#include <asynPortDriver.h>
#include <wiringPi.h>
#include <epicsExport.h>
static const char *driverName = "GPIOAsynDriver";
#define digitalOutputString "DIGITAL_OUTPUT"
#define NUM_IO_BITS 2 // Number of digital I/O bits to USE
class GPIOAsynDriverOut : public asynPortDriver {
public:
GPIOAsynDriverOut(const char *portName);
/* These are the methods that we override from asynPortDriver */
virtual asynStatus writeUInt32Digital(asynUser *pasynUser, epicsUInt32 value, epicsUInt32 mask);
virtual void report(FILE *fp, int details);
protected:
// Analog output parameters
int digitalOutput_;
#define FIRST_GPIOOUT_PARAM digitalOutput_
#define LAST_GPIOOUT_PARAM digitalOutput_
private:
int gpio[2];
void init_GPIO_Out();
asynStatus setGPIO(int index, int val);
};
#define NUM_PARAMS ((int)(&LAST_GPIOOUT_PARAM - &FIRST_GPIOOUT_PARAM + 1))
GPIOAsynDriverOut::GPIOAsynDriverOut(const char *portName)
: asynPortDriver(portName, 1 , NUM_PARAMS,
asynUInt32DigitalMask | asynDrvUserMask, // Interfaces that we implement
asynUInt32DigitalMask, // Interfaces that do callbacks
ASYN_MULTIDEVICE | ASYN_CANBLOCK, 1, /* ASYN_CANBLOCK=1, ASYN_MULTIDEVICE=1, autoConnect=1 */
0, 0) /* Default priority and stack size */
{
// Digital I/O parameters
init_GPIO_Out();
createParam(digitalOutputString, asynParamUInt32Digital, &digitalOutput_);
}
asynStatus GPIOAsynDriverOut::writeUInt32Digital(asynUser *pasynUser, epicsUInt32 value, epicsUInt32 mask)
{
int function = pasynUser->reason;
int status=0;
int i;
epicsUInt32 outValue=0, outMask;
static const char *functionName = "writeUInt32Digital";
setUIntDigitalParam(function, value, mask);
if (function == digitalOutput_) {
for (i=0, outMask=1; i<NUM_IO_BITS; i++, outMask = (outMask<<1)) {
// Only write the value if the mask has this bit set
outValue = ((value &outMask) == 0) ? 0 : 1;
if ((mask & outMask ) != 0) {
status = setGPIO(i, outValue);
}
}
}
if (status == 0) {
asynPrint(pasynUser, ASYN_TRACEIO_DRIVER,
"%s:%s, port %s, wrote outValue=0x%x, value=0x%x, mask=0x%x\n",
driverName, functionName, this->portName, outValue, value, mask);
} else {
asynPrint(pasynUser, ASYN_TRACE_ERROR,
"%s:%s, port %s, ERROR writing outValue=0x%x, value=0x%x, mask=0x%x, status=%d\n",
driverName, functionName, this->portName, outValue, value, mask, status);
}
return (status==0) ? asynSuccess : asynError;
}
void GPIOAsynDriverOut::init_GPIO_Out()
{
int i;
this->gpio[0] = 9;
this->gpio[1] = 10;
wiringPiSetup();
for (i = 0; i < NUM_IO_BITS ; i++){
pinMode(this->gpio[i], OUTPUT);
digitalWrite(this->gpio[i], 0);
}
}
asynStatus GPIOAsynDriverOut::setGPIO(int index, int val)
{
digitalWrite(this->gpio[index], val);
return asynSuccess;
}
void GPIOAsynDriverOut::report(FILE *fp, int details)
{
fprintf(fp, " Port: %s,GPIO %d - %d\n", this->portName, this->gpio[0], this->gpio[1]);
asynPortDriver::report(fp, details);
}
extern "C" int GPIOAsynDriverOutConfig(const char *portName)
{
GPIOAsynDriverOut *pGPIOAsynDriverOut = new GPIOAsynDriverOut(portName);
pGPIOAsynDriverOut = NULL;
return(asynSuccess);
}
static const iocshArg configArg0 = { "Port name", iocshArgString};
static const iocshArg * const configArgs[] = {&configArg0,};
static const iocshFuncDef configFuncDef = {"GPIOAsynDriverOutConfig", 1, configArgs};
static void configCallFunc(const iocshArgBuf *args)
{
GPIOAsynDriverOutConfig(args[0].sval);
}
void drvGPIOAsynDriverOutRegister(void)
{
iocshRegister(&configFuncDef,configCallFunc);
}
extern "C" {
epicsExportRegistrar(drvGPIOAsynDriverOutRegister);
}编写一个数据库定义文件：
# drvgpioasyn.dbd
registrar(drvGPIOAsynDriverOutRegister)
在同级目录下的Makefile中指定需要的数据库定义文件，库文件以及源文件：
TOP=../..
include $(TOP)/configure/CONFIG
#----------------------------------------
# ADD MACRO DEFINITIONS AFTER THIS LINE
#=============================
#=============================
# Build the IOC application
PROD_IOC = gpioasyn
# gpioasyn.dbd will be created and installed
DBD += gpioasyn.dbd
# gpioasyn.dbd will be made up from these files:
gpioasyn_DBD += base.dbd
gpioasyn_DBD += asyn.dbd
gpioasyn_DBD += drvgpioasyn.dbd
# Include dbd files from all support applications:
#gpioasyn_DBD += xxx.dbd
# Add all the support libraries needed by this IOC
gpioasyn_LIBS += asyn
gpioasyn_LIBS += wiringPi
wiringPi_DIR = /usr/lib
gpioasyn_SRCS += drvgpioasyn.cpp
# gpioasyn_registerRecordDeviceDriver.cpp derives from gpioasyn.dbd
gpioasyn_SRCS += gpioasyn_registerRecordDeviceDriver.cpp
# Build the main IOC entry point on workstation OSs.
gpioasyn_SRCS_DEFAULT += gpioasynMain.cpp
gpioasyn_SRCS_vxWorks += -nil-
# Add support from base/src/vxWorks if needed
#gpioasyn_OBJS_vxWorks += $(EPICS_BASE_BIN)/vxComLibrary
# Finally link to the EPICS Base libraries
gpioasyn_LIBS += $(EPICS_BASE_IOC_LIBS)
#===========================
include $(TOP)/configure/RULES在Db/目录下，定义数据库模板文件digitalout.template，在此仅定义了一个数字量输出记录bo，用于写GPIO管脚：
record(bo, "$(P)$(R)")
{
field(PINI, "$(PINI=YES)")
field(DESC, "$(DESC=)")
field(DTYP, "asynUInt32Digital")
field(OUT, "@asynMask($(PORT),$(ADDR),$(MASK))DIGITAL_OUTPUT")
field(ZNAM, "$(ZNAM=Low)")
field(ZSV, "$(ZSV=NO_ALARM)")
field(ONAM, "$(ONAM=High)")
field(OSV, "$(OSV=NO_ALARM)")
}将这个模板文件添加到同级的Makefile文件中。
返回这个IOC的顶层目录，执行make，编译整个项目。
进入启动目录cd iocBoot/iocgpioasyn/，编辑以下文件：
1） digitalout.substitutions
file "$(TOP)/db/digitalout.template"
{
pattern
{ R, MASK, ADDR}
{Bo1, 0x01, 0}
{Bo2, 0x02, 0}
}2） st.cmd:
orangepi@orangepi4-lts:/usr/local/EPICS/program/gpioasyn/iocBoot/iocgpioasyn$ cat st.cmd
#!../../bin/linux-aarch64/gpioasyn
#- You may have to change gpioasyn to something else
#- everywhere it appears in this file
< envPaths
cd "${TOP}"
## Register all support components
dbLoadDatabase "dbd/gpioasyn.dbd"
gpioasyn_registerRecordDeviceDriver pdbbase
GPIOAsynDriverOutConfig("GPIO")
cd "${TOP}/iocBoot/${IOC}"
dbLoadTemplate("digitalout.substitutions","P=TEST:,PORT=GPIO,ADDR=0,TIMEOUT=1")
iocInit
启动程序，进行测试：
root@orangepi4-lts:/usr/local/EPICS/program/gpioasyn/iocBoot/iocgpioasyn# ../../bin/linux-aarch64/gpioasyn st.cmd
#!../../bin/linux-aarch64/gpioasyn
< envPaths
epicsEnvSet("IOC","iocgpioasyn")
epicsEnvSet("TOP","/usr/local/EPICS/program/gpioasyn")
epicsEnvSet("SUPPORT","/usr/local/EPICS/synApps/support")
epicsEnvSet("EPICS_BASE","/usr/local/EPICS/base")
cd "/usr/local/EPICS/program/gpioasyn"
## Register all support components
dbLoadDatabase "dbd/gpioasyn.dbd"
gpioasyn_registerRecordDeviceDriver pdbbase
## Load record instances
#dbLoadRecords("db/gpioasyn.db","user=orangepi")
GPIOAsynDriverOutConfig("GPIO")
cd "/usr/local/EPICS/program/gpioasyn/iocBoot/iocgpioasyn"
dbLoadTemplate("digitalout.substitutions","P=TEST:,PORT=GPIO,ADDR=0,TIMEOUT=1")
iocInit
Starting iocInit
############################################################################
## EPICS R7.0.7
## Rev. 2023-06-25T15:48+0000
## Rev. Date build date/time:
############################################################################
iocRun: All initialization complete
## Start any sequence programs
#seq sncxxx,"user=orangepi"
epics> dbl
TEST:Bo1
TEST:Bo2
用caput对IOC中加载的两个bo记录进行写1和写0，可以测量到GPIO对应管脚上电平的变化。
