@TDK Hi! I am sorry for this! I've not used it until now! Let me redo it! I will also use the current version that I have.
Reading it I can see that I have provided no explanation whatsoever, so here is my ongoing goal.
NOTE: This is the first time I work with ADC and try to control a touchscreen myself.
I was able to design a new board using a STM32F469IIT6, besides other things that I have added onto the board, the current question is regarding my intention on controlling the touchscreen. Since it is a prototype, I have connected the pins for the screen in two ways, which I can control the direction using 4 jumpers. The first way that I can get control of the touchscreen is using a XPT2046 that I have added to the board, in case of not being able to use the ADC, so I would have something to work on, until I could fix any wiring mistake when trying to control it directly with ADC pins.
So, I was able to control it with the XPT2046, however it is very slow doing this way, since first I have to send command using SPI, which already takes time, and what is worse, I have to reduce the Baud Rate, because the XPT is slower than my STM. Therefore, my goal is now to migrate from using a external controller and drive the touch screen directly.
Working with the ADC, I was then able to read the signal, and the response is much, much better than when using the XPT. However, the only challenge I am currently facing is to set up an interrupt. I can't use the polling mode because I have other communications that I am expecting to receive from external devices and then I can't be blocking them to read the screen.
I've set up my ADC as follow, I will put it into 2 parts:
PART I - ADC configuration
static void MX_ADC1_Init(void)
{
/* USER CODE BEGIN ADC1_Init 0 */
/* USER CODE END ADC1_Init 0 */
ADC_AnalogWDGConfTypeDef AnalogWDGConfig = {0};
ADC_ChannelConfTypeDef sConfig = {0};
/* USER CODE BEGIN ADC1_Init 1 */
/* USER CODE END ADC1_Init 1 */
/** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
*/
hadc1.Instance = ADC1;
hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4;
hadc1.Init.Resolution = ADC_RESOLUTION_12B;
hadc1.Init.ScanConvMode = ENABLE;
hadc1.Init.ContinuousConvMode = ENABLE;
hadc1.Init.DiscontinuousConvMode = DISABLE;
hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
hadc1.Init.NbrOfConversion = 2;
hadc1.Init.DMAContinuousRequests = DISABLE;
hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
if (HAL_ADC_Init(&hadc1) != HAL_OK)
{
Error_Handler();
}
/** Configure the analog watchdog
*/
AnalogWDGConfig.WatchdogMode = ADC_ANALOGWATCHDOG_SINGLE_REG;
AnalogWDGConfig.HighThreshold = 0;
AnalogWDGConfig.LowThreshold = 0;
AnalogWDGConfig.Channel = ADC_CHANNEL_9;
AnalogWDGConfig.ITMode = ENABLE;
if (HAL_ADC_AnalogWDGConfig(&hadc1, &AnalogWDGConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
*/
sConfig.Channel = ADC_CHANNEL_9;
sConfig.Rank = 1;
sConfig.SamplingTime = ADC_SAMPLETIME_3CYCLES;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
*/
sConfig.Channel = ADC_CHANNEL_10;
sConfig.Rank = 2;
if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN ADC1_Init 2 */
/* USER CODE END ADC1_Init 2 */
}
PART II - ADC callback
void HAL_ADC_LevelOutOfWindowCallback(ADC_HandleTypeDef* hadc)
{
if (hadc->Instance == ADC1) {
adcs[0] = HAL_ADC_GetValue(hadc);
adcs[1] = HAL_ADC_GetValue(hadc);
cmd = 0x01;
__HAL_ADC_CLEAR_FLAG(hadc, ADC_FLAG_AWD);
__HAL_ADC_CLEAR_FLAG(hadc, ADC_FLAG_EOC);
__HAL_ADC_CLEAR_FLAG(hadc, ADC_FLAG_OVR);
HAL_ADC_Start_IT(hadc);
}
}
With this, I was able to read the screen and use the interrupt but with some issues.
1) I expected to have 0 or a low value when trying nothing was touching the screen, however I constantly read a value that stands between the maximum value I can get and the minimum value I can get when I touch the screen. With this issue I would have to sacrifice part of the screen as non-detectable almost in the middle of the screen.
2) I did then set the watchdog "safeguard" region, to test if it would work, however for some reason, every time the reading hit a value within the safeguard range, the ADC_IT stopped triggering, as if it was in some race condition. I could confirm that the while loop works just fine, but it never went to the callback again.
Along with this, I also have a question regarding the way I am trying to use the ADC. Here is my schematic:
The ADC pins are connected to the touch screen in this very straightforward way. I wonder if this approach was correct, or if I am missing some pull up/down. Because, if I am not getting it wrongly, I need to drive the pins from left/right to right/left and read from up/down to down/up. It was very easy to do, however once I do it, I have then to change the GPIO configurations for all 4 pins. My concern is, if this approach is correct or if I should add some component to my schematic. I've tried to forcedly drive the pins with others. connecting them together, but the readings were terrible.
I really appreciate the patient you all have been having with my questions!
If needed I can also provide the whole schematic.
