On 03/31/2016 09:55 PM, didier derny wrote: > cs is low for the entire phi2 cycle > phi2 in blue, cs in red > > cs is build from a cs from the bus subdivided by a 74ls138 + 74ls04 OK, that could be a problem since the addresses become valid somewhere in the middle of PHI2 being low. That's why when using a RAM, you make sure R/W can only become LOW while PHI2 is HIGH, otherwise you will destroy data. Try to limit CS going LOW to the period when the addresses match _and_ PHI2 is high. Gerrit > > > > On 31/03/2016 21:45, Gerrit Heitsch wrote: >> On 03/31/2016 09:35 PM, didier derny wrote: >>> Finally it works at even and odd addresses >>> >>> I observed both case with the oscilloscope ODD and EVEN addresses >>> >>> the differences between both case was that when the code was at odd >>> addresses >>> the A0 line was at the same value for the next cycle, >>> so the hypothesis was that CH376 was removing the data to fast when A0 >>> changed... >>> >>> so I added a small capacitor between A0 and GND (on the CH376) >>> >>> now A0 is delayed and it works where ever is the code (odd/even) >>> >>> how could I solve this problem properly ? >>> I don't like this capacitor on the address bus... >> >> You still didn't tell us if CS is low while PHI2 is high or not. >> Mixing this up would explain your problem... >> >> Gerrit >> >> >> >> >>> >>> thanks to all >>> >>> -- >>> didier >>> >>> >>> On 30/03/2016 22:08, Gerrit Heitsch wrote: >>>> On 03/30/2016 09:44 PM, didier derny wrote: >>>>> if I remove the board and inject a signal on A0 >>>>> I get the signals on other pins a few mv >>>>> a little bit higher on CS >>>>> >>>>> I checked with the oscilloscope >>>>> >>>>> CS / PHI2 with the code odd/even seems ok cs go low on falling edge >>>>> of phi2 / go up on raising edge of phi2 (same for odd and even) >>>> >>>> Huh? According to what I could find, CS is low_active on that chip. >>>> Meaning you need to have CS low when PHI2 is high. >>>> >>>> Gerrit >>>> >>>> >>>> >>>> Message was sent through the cbm-hackers mailing list >>> >>> >>> Message was sent through the cbm-hackers mailing list >>> >>> >> >> >> Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing listReceived on 2016-03-31 21:00:03
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