Why don't I get HIGH on output pins of MCP23S17? - c

Question

I use a STM32 connected with SPI to a MCP23S17 16 bit I/O port expander.
I want to make all 16 I/0 pins as output and just making them all LOW or HIGH.
I used an oscilloscope to check is SPI transmit the signals right, and it does.
The only thing is that on the I/O pins I get around 0.4V. Not 5V.
Sometimes I get a value of 1.4V but it goes away, weird thing...
Can somebody check my code and tell me where is my mistake? I am pretty sure I did the code wrong somewhere.
MCP23S17.h:
#ifndef INC_MCP23S17_H_
#define INC_MCP23S17_H_
#include "stm32f1xx_hal_conf.h"
extern SPI_HandleTypeDef hspi2;
void MCP23S17_SPI_Write(uint8_t reg_addr, uint8_t data);
uint8_t MCP23S17_SPI_Read(uint8_t data);
#define CS_HIGH() HAL_GPIO_WritePin(GPIOB, GPIO_PIN_2, GPIO_PIN_RESET);
#define CS_LOW() HAL_GPIO_WritePin(GPIOB, GPIO_PIN_2, GPIO_PIN_SET);
#define MCP23S17_AAA ((uint8_t)0x0E)
#define MCP23S17_ADDRESS ((uint8_t)0x40)
#define MCP23S17_W ((uint8_t)0x00)
#define MCP23S17_R ((uint8_t)0x01)
#define MCP23S17_IODIRA ((uint8_t)0x00)
#define MCP23S17_IPOLA ((uint8_t)0x02)
#define MCP23S17_GPINTENA ((uint8_t)0x04)
#define MCP23S17_DEFVALA ((uint8_t)0x06)
#define MCP23S17_INTCONA ((uint8_t)0x08)
#define MCP23S17_IOCONA ((uint8_t)0x0A)
#define MCP23S17_GPPUA ((uint8_t)0x0C)
#define MCP23S17_INTFA ((uint8_t)0x0E)
#define MCP23S17_INTCAPA ((uint8_t)0x10)
#define MCP23S17_GPIOA ((uint8_t)0x12)
#define MCP23S17_OLATA ((uint8_t)0x14)
#define MCP23S17_IODIRB ((uint8_t)0x01)
#define MCP23S17_IPOLB ((uint8_t)0x03)
#define MCP23S17_GPINTENB ((uint8_t)0x05)
#define MCP23S17_DEFVALB ((uint8_t)0x07)
#define MCP23S17_INTCONB ((uint8_t)0x09)
//#define MCP23S17_IOCONB ((uint8_t)0x0B)
#define MCP23S17_GPPUB ((uint8_t)0x0D)
#define MCP23S17_INTFB ((uint8_t)0x0F)
#define MCP23S17_INTCAPB ((uint8_t)0x11)
#define MCP23S17_GPIOB ((uint8_t)0x13)
#define MCP23S17_OLATB ((uint8_t)0x15)
//#define MCP23S17_INT_ERR ((uint8_t)255)
//#define BANK ((uint8_t)0x80) //bit 7 of IOCON
//#define MIRROR ((uint8_t)0x40) //bit 6 of IOCON
//#define SEQOP ((uint8_t)0x20) //bit 5 of IOCON
//#define DISSLW ((uint8_t)0x10) //bit 4 of IOCON
//#define HAEN ((uint8_t)0x08) //bit 3 of IOCON
//#define ODR ((uint8_t)0x04) //bit 2 of IOCON
//#define INTPOL ((uint8_t)0x02) //bit 1 of IOCON
//#define unused ((uint8_t)0x00) //bit 0 of IOCON
//-----------------------
#define MCP23S17_MODERA_W(x) MCP23S17_SPI_Write(MCP23S17_IODIRA, ((uint8_t)x))
#define MCP23S17_MODERA_R() MCP23S17_SPI_Read(MCP23S17_IODIRA)
#define MCP23S17_IPOLA_W(x) MCP23S17_SPI_Write(MCP23S17_IPOLA, ((uint8_t)x))
#define MCP23S17_ODRA_W(x) MCP23S17_SPI_Write(MCP23S17_OLATA, ((uint8_t)x))
#define MCP23S17_ODRA_R() MCP23S17_SPI_Read(MCP23S17_OLATA)
#define MCP23S17_IDRA_R() MCP23S17_SPI_Read(MCP23S17_GPIOA) // Reflect the value of the port A
#define MCP23S17_PUDA_W(x) MCP23S17_SPI_Write(MCP23S17_GPPUA, ((uint8_t)x))
#define MCP23S17_PUDA_R() MCP23S17_SPI_Read(MCP23S17_GPPUA)
#define MCP23S17_SETUP_W(x) MCP23S17_SPI_Write(MCP23S17_IOCONA, ((uint8_t)x))
#define MCP23S17_SETUP_R() MCP23S17_SPI_Read(MCP23S17_IOCONA))
#define MCP23S17_MODERB_W(x) MCP23S17_SPI_Write(MCP23S17_IODIRB, ((uint8_t)x))
#define MCP23S17_MODERB_R() MCP23S17_SPI_Read(MCP23S17_IODIRB)
#define MCP23S17_IPOLB_W(x) MCP23S17_SPI_Write(MCP23S17_IPOLB, ((uint8_t)x))
#define MCP23S17_ODRB_W(x) MCP23S17_SPI_Write(MCP23S17_OLATB, ((uint8_t)x))
#define MCP23S17_ODRB_R() MCP23S17_SPI_Read(MCP23S17_OLATB)
#define MCP23S17_IDRB_R() MCP23S17_SPI_Read(MCP23S17_GPIOB) // Reflect the value of the port B
#define MCP23S17_PUDB_W(x) MCP23S17_SPI_Write(MCP23S17_GPPUB, ((uint8_t)x))
#define MCP23S17_PUDB_R() MCP23S17_SPI_Read(MCP23S17_GPPUB)
//-----------------------
void GPIO_Write_Pins(uint16_t);
void GPIO_Expander_Init();
void MCP23S17_SPI_Write(uint8_t reg_addr, uint8_t data);
#endif /* INC_MCP23S17_H_ */
MCP23S17.c
#include "main.h"
#include "MCP23S17.h"
void MCP23S17_SPI_Write(uint8_t reg_addr, uint8_t data)
{
uint8_t pBuff[3];
pBuff[0] = MCP23S17_ADDRESS|MCP23S17_AAA|MCP23S17_W; //optocode that contain 0100 + 111 + 0 (read command)
pBuff[1] = reg_addr; // register address
pBuff[2] = data; // the value that is modified on the register, check datasheet
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);
HAL_SPI_Transmit_IT(&hspi2, pBuff, 3); //transmit on the spi2 the optocode, register adress and the value for the register
for(uint32_t i = 0; i < 85; i++) //delay
{}
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);
}
void GPIO_Expander_Init()
{
MCP23S17_SETUP_W(0x00);
MCP23S17_MODERA_W(0x00);
MCP23S17_MODERB_W(0x00);
MCP23S17_PUDA_W(0x00);
MCP23S17_PUDB_W(0x00);
//MCP23S17_IPOLA_W(0x00);
//MCP23S17_IPOLB_W(0x00);
}
void GPIO_Write_Pins(uint16_t dataspi)
{
//16 to 8 and 8
uint8_t data_half[2];
data_half[0]=*((uint8_t*)&(dataspi)+1); //split the first half of the data
data_half[1]=*((uint8_t*)&(dataspi)+0); //split the second half of the data
MCP23S17_ODRA_W(data_half[0]); //first half
MCP23S17_ODRB_W(data_half[1]); //second half
}
and in main.c
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_SET);
GPIO_Expander_Init();
GPIO_Write_Pins(0xFFFF);
while(1)
{
}

Answer 1

The only thing is that on the I/O pins I get around 0.4V
This is likely because GPIOs are not initialized.
You also have a different problem to deal with.
for(uint32_t i = 0; i < 85; i++) //delay
{}
This loop is very likely to be optimize away by the compiler. This is because, it doesn't do anything.
There are more sophisticated ways of generating delays in a microcontroller. The best possible solution would be to use a timer module.

Answer 2

So coming back with the solution, the code was good, 2 first gpio expanders that I tried were purely burned. For a much shorter working code just comment here asking for it. Thank everyone for advices cause I took them in consideration in the final form of code.