Cypress CY3674, User Manual

Page: 91 / 117

EZ-USB Development Kit User Guide, Doc. # 001-66390 Rev. *D 91
EZ-USB Development Kit Firmware Examples
//Clear Flags
EXIF &= 0xBF; // Clear INT4 EXIF.6 Flag
EXIF &= 0x7F; // Clear INT5 EXIF.7 Flag
EICON &= 0xF7; // Clear INT6 EICON.3 Flag
EA = 1; // Enable Global Interrupt
The Interrupt service routines for each of these external interrupts are defined in "isr.c". These rou-
tines clear the interrupt and toggle the relevant port pin and any one of the LEDs from D2 to D5.
void ISR_EXTR4(void) interrupt 10
{
EXIF &= 0xBF; // Clear INT4 EXIF.6 Flag
IOC ^= 0x10; // Toggle pin 4 of PortC
}
The example is compiled using the Keil IDE similar to previous examples and corresponding images
for RAM (extr_intr.hex) and EEPROM (extr_intr.iic) can be generated. Both the images are located
at
<Installed_directory>\<version\extr_intr
. Download the images using the process
outlined in Method to Download Firmware Image to EZ-USB Internal RAM Memory on page 69 and
Method to Download Firmware Image to External I2C EEPROM on page 69 .
8.12.1 Testing the Example
The function generator can be set to generate a square wave of a known frequency (use a low fre-
quency - for example, a 100-Hz signal to view LED toggling). When the respective interrupts are trig-
gered, the LED toggle appears. When an INT0 interrupt occurs, PC.0 and D2 are toggled. Similarly,
on INT1/ INT4/ INT5/ INT6, PC.1 and D3/ PC.4 and D4/ PC.5 and D5/ PC.6 are toggled. Port C pin
toggling can be checked by connecting those pins to the DSO.
8.13 Vend_ax Example
This example demonstrates the use of different vendor commands. Vendor commands are used to
accomplish unique tasks, such as EZ-USB reset, RAM download, setting different frequency for the
I2C interface of EZ-USB, communicate with an external SRAM memory, and so on. The vendor
commands are defined in the
vend_ax.c source file of the example. Open the project by clicking on
vend_ax.uv2 .
Table 8-4. Port Pins and External Interrupt Mapping
Pin Name
Port/Jumper name on
CY3684/CY3674
Port C P3
LEDs JP3
INT0 P2.19
INT1 P2.18
INT4 P6.5
INT5 P6.4
INT6 PE.5