Converting PCB from SX20 to SX48
smt52
Posts: 11
Hi,
We are converting our PCB from the SX20 to the SX48. The new SX48 based PCB doesn't work.
Am I correct in assuming that I just change SX20 to SX48 in the DEVICE section in the assembly?
Shane.
p.s. We are using the same identical I/O lines on the SX48 compared to the SX20.
p.p.s. The primary reason for the switch is double flash/ram, plus the fact that the SX48 going to be Pb-free, unlike the SX20.
Post Edited (smt52) : 7/31/2005 4:42:22 AM GMT
We are converting our PCB from the SX20 to the SX48. The new SX48 based PCB doesn't work.
Am I correct in assuming that I just change SX20 to SX48 in the DEVICE section in the assembly?
Shane.
p.s. We are using the same identical I/O lines on the SX48 compared to the SX20.
p.p.s. The primary reason for the switch is double flash/ram, plus the fact that the SX48 going to be Pb-free, unlike the SX20.
Post Edited (smt52) : 7/31/2005 4:42:22 AM GMT
Comments
A possible issue:
The SX48 and SX52 both use $08 and $09 ram registers for RD and RE I/O ports respectively. In the SX20 both of these registers are free for general use. If you are not using these ports, I suppose that you could get away with using them as general purpose ram, but they would have to be set as outputs with nothing connected before any values could be written and held. It is far better to just not use them at all for your application (I am assuming that RD and RE are not connected). Another issue is that the bank address structure is different between the SX20 and SX48, given your explanation of the application you probably knew this already. And yes, using the SX48 device directive is appropriate and necessary.
JT
All JT said above is true, but in addition, the method of accessing the MODE (M) register is different, hence setting I/O directions would be affected. You cannot write a literal directly to the M register, you must go through the W register.
Furthermore, the M codes are different for the SX 48/52.
Hope this helps,
Cheers,
Peter (pjv)