| ??? 12/06/06 12:35 Read: times |
#129066 - answer to "why": Responding to: ???'s previous message |
Priyanka Gupta said:
According to my schematic i have tested my hardware , all connections are connected in a right way and i also told here my program is working with taking datatype int but it will not work with datatype "char" , so for that i want help why it should occurs ?? This will occur if the 8052 cannot drive the SRAM's A0 pin low, either because it is not connected to the address latch ('573), or the corresponding input of the address latch is not connected to the 8052, or one of these is connected to VCC. In the latter case, the corresponding output of 8052 or the address latch might already have been damaged permanently, even if the short to VCC has been already removed. Try to figure out for yourself what happens if the memory sees only odd addresses, even if the program tries to write/read to/from even address. The opposite (stuck-at low of A0) might also be the case. You might want to write a small little program doing nothing just writing 0 into P0.0 and ending in a loop, run it and measure what is on pins 9 and 12 of '573; then repeat the same but now writing 1 into P0.0. JW |
