EEPROM SPI Reading issue

[Siva21]

Hello, 

I am trying to write and read from stm32f105 to an eeprom 93AA46A, using Full-Duplex Master. 

To write into the eeprom, I am using following code:

void EEPROM_WriteEnable(void)
{
 uint8_t cmd = EEPROM_CMD_WRITE_ENABLE; //0x98

 EEPROM_CS_HIGH();
 HAL_Delay(1);

 HAL_SPI_Transmit(&hspi1, &cmd, 1, HAL_MAX_DELAY);

 EEPROM_CS_LOW();
}
void EEPROM_WriteByte(uint8_t address, uint8_t data)
{
 uint8_t txData[3];
 // Enable Write Operation
 EEPROM_WriteEnable();

 // Prepare Write Command (101xxxxx | 6-bit address)
	txData[0] = EEPROM_CMD_WRITE; //0xA0
	txData[1] = 0x00; //address
	txData[2] = 0x55; // Data

	// Send Write Command
	EEPROM_CS_HIGH();
	HAL_Delay(1);

	HAL_SPI_Transmit(&hspi1, txData, 3, HAL_MAX_DELAY);

	EEPROM_CS_LOW();
}

 

and to read from EEPROM, I have follwoing code:

void EEPROM_ReadByte(uint8_t address)
{
uint8_t txData_read[3];
uint8_t rxData = 0;

	txData_read[0] = EEPROM_CMD_READ; //0xC0
	txData_read[1] = 0x00; //address
	txData_read[2] = 0x01; // dummy

 EEPROM_CS_HIGH();
 HAL_Delay(1);
 HAL_SPI_Transmit(&hspi1, txData_read, 3, HAL_MAX_DELAY);

 HAL_SPI_Receive(&hspi1, rxData, 1, HAL_MAX_DELAY);

 EEPROM_CS_LOW();
}

 

I don't get anything from eeprom, the HAL_SPI_Receive doesn't make anything. Is there anyone that can verify that the code is correct?

Thank you.

[Andrew Neil]

Welcome to the forums.

 

---

@Siva21 wrote:

I am trying to write and read from stm32f105 to an eeprom 93AA46A

---

Please give full details of your hardware - see: 

How to write your question to maximize your chances to find a solution.

 

Use  HAL_SPI_TransmitReceive()rather than separate transmit & receive:

https://community.st.com/t5/stm32-mcus-products/what-is-hal-spi-transmitreceive-purpose-and-how-it-works/td-p/337551

 

Have you used an oscilloscope or logic analyser to see what's actually happening on the wires?

[Siva21]

Thank you for your reply. 

Here is the diagram:

The supply voltage is wrong and it is 3.3V. 

I have also tried without pull-up resistor. 

I do have an oscilloscope, and the DO trigger from low to high, when HAL_SPI_Receive or HAL_SPI_TransmitReceive are called. 

[Andrew Neil]

Sorry, those images are too low resolution to read.

Are the EEPROM & STM32 on the same board? Is it a custom board? Or what?

SPI shouldn't need pullups - the lines should be actively driven both high & low.

 

---

@Siva21 wrote:

I do have an oscilloscope, and the DO trigger from low to high, when HAL_SPI_Receive or HAL_SPI_TransmitReceive are called. 

---

and what else happens? It's a 4-wire interface!

As @mƎALLEm said, check your scope traces against the specifications in the EEPROM's datasheet.

[mƎALLEm]

Hello,

93AA46 is a Microchip EEPROM.

Need to read the datasheet especially the electrical characteristics: SPI frequency, Clock polarity etc .. and configure the SPI accordingly. You need also to probe MOSI/MISO/CLK to debug and understand what is going on to know which part of the communication is not working correctly.

[mƎALLEm]

Start by checking your SPI CLK frequency according the the max clock mentioned in the memory datasheet:

+ You're using F1 family. Some IOs are not Five volt Tolerant (FT). As your memory is powered by 5V, are you sure your are not connecting EEPROM_DO output to one of the non-FT IOs?

 

[Siva21]

The eeprom is powered by 3.3V now. It was a mistake which it is fixed now. 

[mƎALLEm]

You still not answered the question: what is the GPIO used for EEPROM DO? If it was not FT it could be damaged.

[bmckenney]

The datasheet I see for the 93AA46A says it's a Microwire device. Microwire is kind of a first-cousin to SPI.

In particular, the request [Ref Table 1-4] is 10 bits, not 8: {1-bit Start, 2-bits Op-code, 7-bits Address}. The Read/Write data is in units of 8-bits. Microwire has no objection to this, but the STM32F105 [Ref RM0008] only supports 8/16-bits, and I don't think I've seen an STM32 where the Rx and Tx frame sizes can be different. (RM0008 also doesn't mention Microwire.)

You may want to consider bit-banging. (There are only 128 bytes, so speed probably isn't a big deal.)

Also: In

> HAL_SPI_Receive(&hspi1, rxData, 1, HAL_MAX_DELAY);

 I expect you meant

> HAL_SPI_Receive(&hspi1, &rxData, 1, HAL_MAX_DELAY);

I'm a bit surprised the compiler didn't object.

[Edit: Fixed some minor specifics. The principle is the same.]

 

[Siva21]

Thank you @bmckenney 

I have implemented bit-banging for SPI, and it works fine now. 

[Andrew Neil]

---

@Siva21 wrote:

I have implemented bit-banging for SPI (sic) 

---

But @bmckenney's point was that it's not SPI - it's Microwire:

 

 

[mƎALLEm]

Unfortunately and according to your schematics, EEPROM DO is connected to PA6 which is not FT IO:

Most probably it was broken while you powered your EEPROM with 5V!