LPC4370 TFBGA100 and SDRAM

[anitsirk]

I'm new to all of these. Is it possible to configure an 8-bit SDRAM to a 100TFLBGA LPC4370? Noticed there's only a single address pin BA0 (EMC_A13) on the 100pin package.

[bernhardfink]

It's possible to connect an 8-bit SDRAM device, shown in Fig 63 in the User Manual.

As you can't cascade devices to a 16-bit or even 32-bit wide memory, you don't need a second Bank Activate pin, you just have one bank available --> one pin.

There are two chip selects EMC_DYCS[1:0] available, so in fact you could connect two 8-bit SDRAM devices.

Regards,

Bernhard.

[anitsirk]

Thank you, bernhardfink! That's very helpful. Most of the 8-bit SDRAMs (IS42S83200G) has a DQM pin but I don't see any recommended connection on the LPC4370's user manual and AN11508 Application Note also, EMC-DQMOUT[3:0] are only available on the LBGA256 package. Can I leave this open on the SDRAM side?

[bernhardfink]

Hi Kristina,

as there is nothing to mask with an 8-bit data bus, the EMC doesn't need to provide such a signal to the SDRAM.

You can simply keep this input on the SDRAM in active state, which means LOW --> pulldown resistor.

If you want to have it flexible for some reason, you can connect a GPIO of the LPC4300 to this pin as well, together with a pulldown. Then you could control from the MCU side with the GPIO if the values on the data bus pins are ignored (= masked) from the SDRAM or accepted.

Regards,

Bernhard.

[anitsirk]

Hi bernhardfink‌, is there a sample code to access the EMC of the LPC4370?

[anitsirk]

Thank you, bernhardfink‌. This answers my question!