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Using the LPC54114 SPI API

Question asked by James Whitney on Mar 20, 2019
Latest reply on Apr 8, 2019 by Alice_Yang

Had a question about the LPC54114 SPI API.

I've been banging my head against the wall for close to two days on something that should seemingly be working. I am trying to read the UID code from a Microchip EEPROM, PN 25AA02UID. It is necessary to provide information on the operation, the address to access, then, read the designated number of bytes.

I used the 'lpcxpresso54114_i2c_polling_b2b_transfer_master' as a template. As a check I ran the original project to check signal generation per a suggestion from Kerry Zhou to a previous inquiry. KZ signals:

 

My results

As no slave is attached MISO (blue trace) is not defined.

Next, I changed the buffer size of srcBuff to '2', destBuff to '4', and connected up the EEPROM. srcBuff[0] = 0x03 and srcBuff[1] = 0xFC. Re-running the program the output is:

While the MOSI pulse (purple trace) looks like a single value I tested with other values other than 0xFC and the address byte and read byte were clearly discernible so I think the trace just looks like a single value due to values 'F' and 'C' being very close. When 'SPI_MasterTransferBlocking' returned all of the values in 'destBuff' were zero, additionally, the MISO signal (Green trace) never showed any indication that data was being clocked out of the EEPROM even though it is clear to see that CS (yellow trace) and SCK (blue trace) are both active.

Anybody have any ideas ?

Jim

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