xPC Target    

DM6804 PWM Capture

This block programs the AMD9513A for capturing PWM signals by using two counters. One counter measures the cycle duration, and the other counter measures the duration the signal is high.

There are two outputs. One output is the relative frequency compared to the base frequency. The other output is the duty cycle. To get the actual frequency, multiply the base frequency by the relative frequency.

Scaling Input to Output

Hardware Output
 Block Input Data Type
 Scaling
TTL
 double
 0 to 1

Driver Block Parameters

Counter - From the list, choose 1&2, 2&3, 3&4, 4&5. This selects which two counters the driver block uses to determine the PWM. In each case, one block is needed for each counter.

Frequency Base - From the list, choose F1=5MHz, F2=500kHz, F3=50kHz, F4=5kHz, or F5=500Hz to set the base frequency. The XTAL frequency is assumed to be 1MHz, therefore the jumper on the DM6804 has to be in position 1MHz not 5MHz.

Sample Time - Enter the base sample time or a multiple of the base sample time. The sample time indicates the update rate of registration on the input (Duty Cycle)

BaseAddress - Enter the base address of the board. This entry must corresponds to the DIP-switch settings on the board. For example, if the base address is 300 (hexadecimal), enter


 DM6804 Counter FM & ARM DM6804 FM Capture