Posted on June 16, 2012 at 10:25
Hi Thierry,
Maybe you could help me with one more thing. I'm attempting to get a reading from a single channel. The board is powered from USB, there's also an ft232 USB<->UART dongle connected to UART1. I'm getting a periodic increase (or decrease) of the reading. This period doesn't seem to have anything with the time - as I play with SysTick there's no noticable effect. Here's the actual example with SysTick firing every second:
Val - 3
Val - 63
Val - 185
Val - 3
Val - 2
Val - 2
Val - 46
Val - 165
Val - 11
Val - 2
Val - 2
Val - 31
Val - 137
Val - 263
Val - 2
Val - 2
Val - 10
Val - 130
Val - 235
Val - 2
Val - 2
If I'd built a graph, you would see that the spikes are very periodic. What confuses me even more is that I had EXACTLY the same picture when playing with touch sensing on PIC MCUs. That is like... my table has pulsing capacity....
Here's the related snippets of the code:
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA | RCC_AHBPeriph_TS, ENABLE);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_3);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_3);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_3);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
union {
uint32_t TSC_CR_Uint32;
struct
{
uint8_t TSCE :1;
uint8_t START :1;
uint8_t AM :1;
uint8_t SYNCPOL :1;
uint8_t IODEF :1;
uint8_t MCV :3;
uint8_t unused :4;
uint8_t PGPSC :3;
uint8_t SSPSC :1;
uint8_t SSE :1;
uint8_t SSD :7;
uint8_t CTPL :4;
uint8_t CTPH :4;
} TSC_CR_Fields;
} TSC_CR_Reg;
TSC_CR_Reg.TSC_CR_Uint32 = 0;
TSC_CR_Reg.TSC_CR_Fields.CTPH = 0xF;
TSC_CR_Reg.TSC_CR_Fields.CTPL = 0xF;
TSC_CR_Reg.TSC_CR_Fields.SSD = 0x40;
TSC_CR_Reg.TSC_CR_Fields.SSE = 0;
TSC_CR_Reg.TSC_CR_Fields.SSPSC = 1;
TSC_CR_Reg.TSC_CR_Fields.PGPSC = 0b011;
TSC_CR_Reg.TSC_CR_Fields.MCV = 0b110;
TSC_CR_Reg.TSC_CR_Fields.IODEF = 0;
TSC_CR_Reg.TSC_CR_Fields.SYNCPOL = 0;
TSC_CR_Reg.TSC_CR_Fields.AM = 0;
TSC_CR_Reg.TSC_CR_Fields.START = 0;
TSC_CR_Reg.TSC_CR_Fields.TSCE = 1;
TSC->CR = TSC_CR_Reg.TSC_CR_Uint32;
TSC->IER = 0x00;
TSC->ICR = 0x03;
TSC->IOHCR &= 0xFFFFFFFD;
//TSC->IOASCR = 0x2;
TSC->IOSCR = 0x4;
TSC->IOCCR = 0x2;
TSC->IOGCSR = 1;
TSC->CR |= 2;
while
(1)
{
if
(flag)
//flag is raised every second
{
GPIOC->ODR ^= GPIO_Pin_8;
//LED
flag = 0;
TSC->ICR = 3;
TSC->CR |= 2;
while
(!(TSC->ISR & 1))
if
(TSC->ISR & 2)
{
TSC->ICR = 3;
TSC->CR |= 2;
printf(
''
Error..
''
);
}
printf(
''
Val - %u
''
, (uint16_t)TSC->IOGXCR[0]);
}
}
