OMAPL138 EMIFA Address Range

John Myc

Other Parts Discussed in Thread: OMAPL138

In our OMAPL138 application we are planning to use the EMIFA asynchronous memory interface operating with a 16 bit data bus.

The datasheet lists the memory range for the asynchronous chip selects as 32 M.

The EMIFA users guide states that the EMIFA address pin EM_A[0] always provides the least significant bit of a 32-bit word address. Therefore, when

interfacing to a 16-bit or 8-bit asynchronous device, the EMA_BA[1] and EMA_BA[0] pins provide the

least-significant bits of the halfword or byte address, respectively.

So for the OMAPL138 which has 24 address lines EMA_A[23:0] plus two bank address lines EMA_BA[1:0]

the total accessable address range would be 16M (64MB)?

over 15 years ago

0 Gus Martinez over 15 years ago

TI__Mastermind 30031 points

Your understanding is correct. With the number of address pins available to the EMIFA, a total of 64MB could be reached. However, the 32MB limit in the memory map makes this impossible. This limitation essentially makes one EMIFA address pin useless. A note(s) regarding this will be added to the next revision of the data sheet.

0 John Myc over 15 years ago in reply to Gus Martinez

Prodigy 50 points

I am a little confused. The memory map lists the address range as 32M (not 32 MB). The EMIFA user guide also states that the EMA_A[0] bits indicates a 32 bit address word (4 bytes). This would imply a total range of 128 MB (32M x 4). So with EMA_A[23:0] and EMA_BA[1:0] you can only access 64MB or half of the range provided. One additional address line would be required to access the complete range.

0 Mukul Bhatnagar over 15 years ago in reply to John Myc

TI__Guru* 85105 points

John

This wiki article should help

http://processors.wiki.ti.com/index.php/Connecting_NOR_Flash_to_OMAP-L138

Let us know if you have follow up questions.

Regards

Mukul

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OMAPL138 EMIFA Address Range