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External Bus Interface on MC9S12XDP512

Question asked by Manuel Schmidberger on Nov 5, 2014
Latest reply on Nov 5, 2014 by lama

Hallo,

 

I use the external bus interface of the MC9S12XDP512 Microcontroller to connect an external Flash. The flash is a 32Mbit, organized as 2Mx16, memory (SST39VF3201B). The following pins are connected with the controller pins (Show attachment).

 

Following settings are made in software:

MMCCTL0 = 0x02; // Enable \CS1

MMCCTL1 = 0x01 // Enable the Flash or ROM in the memory map

MODE = 0xA0; // Normal expanded mode - bus enabled

EBICTL0 = 0x36; // High byte enable and ADDR21:1

EBICTL1 = 0x02; // Stretch = 3cycles

 

 

When I read from memory, following happens:

 

Unsigned int data = *((unsigned int *far)0x200001);

-> ADDR1 is set to 1  -> OK

 

Unsigned int data = *((unsigned int *far)0x200002);

-> ADDR1 is set to 0  -> OK

-> ADDR2 is set to 0  -> Why not 1?

 

Unsigned int data = *((unsigned int *far)0x200003);

-> ADDR1 is set to 0  -> Why not 1?

-> ADDR2 is set to 1  -> OK

 

Is there something wrong?

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