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olsndot/firmware/main.c

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/* OpenStep 2
* Copyright (C) 2017 Sebastian Götte <code@jaseg.net>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
/* Preliminary remarks.
*
* This code is intended to run on an ARM Cortex-M0 microcontroller made by ST, part number STM32F030F4C6
*
* Some terminology:
*
* * The term "raw channel" refers to a single output of the 32 outputs provided by the driver board. It corresponds to
* a single color sub-channel of one RGBW output. One RGBW output consists of four raw channels.
*
* * The term "logical channel" refers to one RGBW output of four individual colors handled by a group of four raw
* channels.
*/
#include <stm32f0xx.h>
#include <stdint.h>
#include <system_stm32f0xx.h>
#include <stm32f0xx_ll_utils.h>
#include <math.h>
/* Bit count of this device. Note that to change this you will also have to adapt the per-bit timer period lookup table
* below.
*/
#define NBITS 14
/* Maximum bit count supported by serial command protocol. The brightness data is assumed to be of this bit width, but
* only the uppermost NBITS bits are used. */
#define MAX_BITS 16
void do_transpose(void);
/* Right-aligned integer raw channel brightness values like so:
*
* bit index 31 ... 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
* | (MSB) serial data put *here* (LSB) |
* |<-utterly ignored->| |<-----------------MAX_BITS------------------>|
* |<----------------NBITS---------------->| |<>|--ignored
* | (MSB) brightness data (LSB) | |<>|--ignored
*/
uint32_t brightness[32] = {
0x23
};
/* Bit-golfed modulation data generated from the above values by the main loop, ready to be sent out to the shift
* registers.
*/
volatile uint32_t brightness_by_bit[NBITS] = { 0 };
/* Global systick timing variables */
uint32_t sys_time = 0;
uint32_t sys_time_seconds = 0;
int main(void) {
/* Get all the good clocks and PLLs on this thing up and running. We're
* running from an external 25MHz crystal, which we're first dividing
* down by 5 to get 5 MHz, then PLL'ing up by 6 to get 30 MHz as our
* main system clock.
*
* The busses are all run directly from these 30 MHz because why not.
*
* Be careful in mucking around with this code since you can kind of
* semi-brick the chip if you do it wrong.
*/
RCC->CR |= RCC_CR_HSEON;
while (!(RCC->CR&RCC_CR_HSERDY));
// HSE ready, let's configure the PLL
RCC->CFGR &= ~RCC_CFGR_PLLMUL_Msk & ~RCC_CFGR_SW_Msk & ~RCC_CFGR_PPRE_Msk & ~RCC_CFGR_HPRE_Msk;
// PLLMUL: 6x (0b0100)
RCC->CFGR |= (0b0100<<RCC_CFGR_PLLMUL_Pos) | RCC_CFGR_PLLSRC_HSE_PREDIV;
// PREDIV:
// HSE / PREDIV = PLL SRC
RCC->CFGR2 &= ~RCC_CFGR2_PREDIV_Msk;
RCC->CFGR2 |= RCC_CFGR2_PREDIV_DIV5; /* prediv :10 -> 5 MHz */
RCC->CR |= RCC_CR_PLLON;
while (!(RCC->CR&RCC_CR_PLLRDY));
RCC->CFGR |= (2<<RCC_CFGR_SW_Pos);
SystemCoreClockUpdate();
SysTick_Config(SystemCoreClock/1000); /* 1ms interval */
/* Enable all the periphery we need */
RCC->AHBENR |= RCC_AHBENR_GPIOAEN | RCC_AHBENR_GPIOBEN;
RCC->APB2ENR |= RCC_APB2ENR_SPI1EN | RCC_APB2ENR_TIM1EN | RCC_APB2ENR_USART1EN | RCC_APB2ENR_ADCEN;
RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
/* Configure all the GPIOs */
GPIOA->MODER |=
(3<<GPIO_MODER_MODER0_Pos) /* PA0 - Current measurement analog input */
| (1<<GPIO_MODER_MODER1_Pos) /* PA1 - RS485 TX enable */
| (2<<GPIO_MODER_MODER2_Pos) /* PA2 - RS485 TX */
| (2<<GPIO_MODER_MODER3_Pos) /* PA3 - RS485 RX */
/* PA4 reserved because */
| (2<<GPIO_MODER_MODER5_Pos) /* PA5 - Shift register clk/SCLK */
| (1<<GPIO_MODER_MODER6_Pos) /* PA6 - LED2 open-drain output */
| (2<<GPIO_MODER_MODER7_Pos) /* PA7 - Shift register data/MOSI */
| (2<<GPIO_MODER_MODER9_Pos) /* FIXME PA9 - Shift register clear (TIM1_CH2) */
| (2<<GPIO_MODER_MODER10_Pos);/* PA10 - Shift register strobe (TIM1_CH3) */
GPIOB->MODER |=
(2<<GPIO_MODER_MODER1_Pos); /* PB1 - Shift register clear (TIM1_CH3N) */
GPIOA->OTYPER |= GPIO_OTYPER_OT_6; /* LED outputs -> open drain */
/* Set shift register IO GPIO output speed */
GPIOA->OSPEEDR |=
(3<<GPIO_OSPEEDR_OSPEEDR5_Pos) /* SCLK */
| (3<<GPIO_OSPEEDR_OSPEEDR6_Pos) /* LED1 */
| (3<<GPIO_OSPEEDR_OSPEEDR7_Pos) /* MOSI */
| (3<<GPIO_OSPEEDR_OSPEEDR10_Pos);/* Strobe */
GPIOB->OSPEEDR |=
(3<<GPIO_OSPEEDR_OSPEEDR1_Pos); /* Clear */
/* Alternate function settings */
GPIOA->AFR[0] |=
(1<<GPIO_AFRL_AFRL2_Pos) /* USART1_TX */
| (1<<GPIO_AFRL_AFRL3_Pos) /* USART1_RX */
| (0<<GPIO_AFRL_AFRL5_Pos) /* SPI1_SCK */
| (0<<GPIO_AFRL_AFRL7_Pos); /* SPI1_MOSI */
GPIOA->AFR[1] |=
(2<<GPIO_AFRH_AFRH2_Pos); /* TIM1_CH3 */
GPIOB->AFR[0] |=
(2<<GPIO_AFRL_AFRL1_Pos); /* TIM1_CH3N */
/* Configure SPI controller */
/* CPOL=0, CPHA=0, prescaler=2 -> 16MBd */
SPI1->CR1 = SPI_CR1_BIDIMODE | SPI_CR1_BIDIOE | SPI_CR1_SSM | SPI_CR1_SSI | SPI_CR1_SPE | (0<<SPI_CR1_BR_Pos) | SPI_CR1_MSTR;
SPI1->CR2 = (0xf<<SPI_CR2_DS_Pos);
/* Configure TIM1 for display strobe generation */
TIM1->CR1 = TIM_CR1_ARPE;
TIM1->PSC = 1; /* Prescale by 2, resulting in a 16MHz timer frequency and 62.5ns timer step size. */
/* CH2 - clear/!MR, CH3 - strobe/STCP */
TIM1->CCMR2 = (6<<TIM_CCMR2_OC3M_Pos) | TIM_CCMR2_OC3PE;
TIM1->CCER |= TIM_CCER_CC3E | TIM_CCER_CC3NE | TIM_CCER_CC3P | TIM_CCER_CC3NP;
TIM1->BDTR = TIM_BDTR_MOE | (1<<TIM_BDTR_DTG_Pos); /* really short dead time */
TIM1->DIER = TIM_DIER_UIE; /* Enable update (overrun) interrupt */
TIM1->ARR = 1;
TIM1->CR1 |= TIM_CR1_CEN;
/* Configure Timer 1 update (overrun) interrupt on NVIC.
* Used only for update (overrun) for strobe timing. */
NVIC_EnableIRQ(TIM1_BRK_UP_TRG_COM_IRQn);
NVIC_SetPriority(TIM1_BRK_UP_TRG_COM_IRQn, 1);
/* Pre-load initial values, kick of first interrupt */
TIM1->EGR |= TIM_EGR_UG;
/* Configure TIM3 for USART timeout handing */
TIM3->CR1 = TIM_CR1_OPM;
TIM3->DIER = TIM_DIER_UIE;
TIM3->PSC = 30;
TIM3->ARR = 1000;
/* Configure Timer 3 update (overrun) interrupt on NVIC.
* Used only for update (overrun) for USART timeout handling. */
NVIC_EnableIRQ(TIM3_IRQn);
NVIC_SetPriority(TIM3_IRQn, 2);
/* Pre-load initial values */
TIM3->EGR |= TIM_EGR_UG;
/* Configure UART for RS485 comm */
/* 8N1, 1MBd */
USART1->CR1 = /* 8-bit -> M1, M0 clear */
/* RTOIE clear */
(8 << USART_CR1_DEAT_Pos) /* 8 sample cycles/1 bit DE assertion time */
| (8 << USART_CR1_DEDT_Pos) /* 8 sample cycles/1 bit DE assertion time */
/* CMIF clear */
/* WAKE clear */
/* PCE, PS clear */
| USART_CR1_RXNEIE
/* other interrupts clear */
| USART_CR1_TE
| USART_CR1_RE;
USART1->CR3 = USART_CR3_DEM; /* RS485 DE enable (output on RTS) */
// USART1->BRR = 30;
USART1->BRR = 40; // 750000
USART1->CR1 |= USART_CR1_UE;
/* Configure USART1 interrupt on NVIC. Used only for RX. */
NVIC_EnableIRQ(USART1_IRQn);
NVIC_SetPriority(USART1_IRQn, 2);
/* Idly loop around, occassionally disfiguring some integers. */
while (42) {
/* Debug output on LED. */
GPIOA->ODR ^= GPIO_ODR_6;
/* Bit-mangle the integer brightness data to produce raw modulation data */
do_transpose();
/* Wait a moment */
for (int k=0; k<10000; k++)
asm volatile("nop");
}
}
/* Modulation data bit golfing routine */
void do_transpose(void) {
/* For each bit value */
for (uint32_t i=0; i<NBITS; i++) {
uint32_t mask = 1<<i<<(MAX_BITS-NBITS); /* Bit mask for this bit value. */
uint32_t bv = 0; /* accumulator thing */
for (uint32_t j=0; j<32; j++) {
if (brightness[j] & mask)
bv |= 1<<j;
}
brightness_by_bit[i] = bv;
}
}
/* Bit timing base value. This is the lowes bit interval used */
#define PERIOD_BASE 4
/* This value is a constant offset added to every bit period to allow for the timer IRQ handler to execute. This is set
* empirically using a debugger and a logic analyzer. */
#define TIMER_CYCLES_FOR_SPI_TRANSMISSIONS 120
/* This is the same as above, but for the reset cycle of the bit period. */
#define RESET_PERIOD_LENGTH 40
/* Defines for brevity */
#define A TIMER_CYCLES_FOR_SPI_TRANSMISSIONS
#define B PERIOD_BASE
/* This is a constant offset containing some empirically determined correction values */
#define C (1 /* reset pulse comp */ - 3 /* analog snafu comp */)
/* This lookup table maps bit positions to timer period values. This is a lookup table to allow for the compensation for
* non-linear effects of ringing at lower bit durations.
*/
static uint16_t timer_period_lookup[NBITS] = {
/* LSB here */
A - C + (B<< 0),
A - C + (B<< 1),
A - C + (B<< 2),
A - C + (B<< 3),
A - C + (B<< 4),
A - C + (B<< 5),
A - C + (B<< 6),
A - C + (B<< 7),
A - C + (B<< 8),
A - C + (B<< 9),
A - C + (B<<10),
A - C + (B<<11),
A - C + (B<<12),
A - C + (B<<13),
/* MSB here */
};
/* Don't pollute the global namespace */
#undef A
#undef B
#undef C
/* Timer 1 main IRQ handler. This is used only for overflow ("update" or UP event in ST's terminology). */
void TIM1_BRK_UP_TRG_COM_IRQHandler(void) {
/* The index of the currently active bit. On entry of this function, this is the bit index of the upcoming period.
* On exit it is the index of the *next* period. */
static int idx = 0;
/* We modulate all outputs simultaneously in n periods, with n being the modulation depth (the number of bits).
* Each period is split into two timer cycles. First, a long one during which the data for the current period is
* shifted out and subsequently latched to the outputs. Then, a short one that is used to reset all outputs in time
* for the next period.
*
* bit value: | <-- least significant, shortest period / most significant, longest period --> |
* bit number: | b0 | b1 | ... | b10 | b11 |
* name: | data cycle | reset cycle | | | | |
* function: | shift data <strobe> wait | | ... | ... | ... | ... |
* duration: | fixed variable | fixed | | | | |
*
* Now, alternate between the two cycles in one phase.
*/
static int clear = 0;
if ((clear = !clear)) {
/* Access bits offset by one as we are setting the *next* period based on idx below. */
uint32_t val = brightness_by_bit[idx];
/* Shift out the current period's data. The shift register clear and strobe lines are handled by the timers
* capture/compare channel 3 complementary outputs. The dead-time generator is used to sequence the clear and strobe
* edges one after another. Since there may be small variations in IRQ service latency it is critical to allow for
* some leeway between the end of this data transmission and strobe and clear. */
SPI1->DR = (val&0xffff);
while (SPI1->SR & SPI_SR_BSY);
SPI1->DR = (val>>16);
while (SPI1->SR & SPI_SR_BSY);
/* Increment the bit index for the next cycle */
idx++;
if (idx >= NBITS)
idx = 0;
/* Set up the following reset pulse cycle. This cycle is short as it only needs to be long enough for the below
* part of this ISR handler routine to run. */
TIM1->ARR = RESET_PERIOD_LENGTH;
TIM1->CCR3 = 1; /* This value is fixed to produce a very short reset pulse. IOs, PCB and shift registers all can
easily handle this. */
} else {
/* Set up everything for the data cycle of the *next* period. The timer is set to count from 0 to ARR. ARR and
* CCR3 are pre-loaded, so the values written above will only be latched on timer overrun at the end of this
* period. This is a little complicated, but doing it this way has the advantage of keeping both duty cycle and
* frame rate precisely constant. */
TIM1->CCR3 = TIMER_CYCLES_FOR_SPI_TRANSMISSIONS;
TIM1->ARR = timer_period_lookup[idx];
}
/* Reset the update interrupt flag. This ISR handler routine is only used for timer update events. */
TIM1->SR &= ~TIM_SR_UIF_Msk;
}
/* The data format of the serial command interface.
*
* The serial interface uses short packets. Currently, there is only one packet type defined: a "set RGBW" packet, using
* command ID 0x23. The packet starts with the command ID, followed by the addressed channel group, followed by four
* times two bytes of big-endian RGBW channel data.
*
*
*/
union packet {
struct {
uint8_t cmd; /* 0x23 */
uint8_t step; /* logical channel. The USART_CHANNEL_OFFX is applied on this number below. */
union {
uint16_t rgbw[4];
struct {
uint16_t r, g, b, w;
};
};
} set_step;
uint8_t data[0];
};
int rxpos = 0;
void TIM3_IRQHandler(void) {
TIM3->SR &= ~TIM_SR_UIF;
/*
if (rxpos != sizeof(union packet)) {
asm("bkpt");
}
*/
rxpos = 0;
}
/* This macro defines the lowest channel number of this board on the serial command bus. On a shared bus with several
* boards, you would generally assign increasing USART_CHANNEL_OFFX values to each one (0, 8, 16, 24, ...).
*
* Example: Let USART_CHANNEL_OFFX be 8.
*
* /--Command channel number received in command packet (packet.set_step.step)
* | /--USART_OFFX
* | | /--4 raw channels per logical channel (step): R, G, B, W
* | | | /--Raw channel offset for R, G, B, W
* | | | | /--Resulting raw channels for R, G, B, W data received in command packet
* | | | | |
* v v v v v
*
* (8 - 8) * 4 + {0, 1, 2, 3} = {0, 1, 2, 3}
* (9 - 8) * 4 + {0, 1, 2, 3}
* (10 - 8) * 4 + {0, 1, 2, 3}
* (11 - 8) * 4 + {0, 1, 2, 3}
* (12 - 8) * 4 + {0, 1, 2, 3}
* (13 - 8) * 4 + {0, 1, 2, 3}
* (14 - 8) * 4 + {0, 1, 2, 3}
* (15 - 8) * 4 + {0, 1, 2, 3}
*/
#ifndef USART_CHANNEL_OFFX
#define USART_CHANNEL_OFFX 0
#endif//USART_CHANNEL_OFFX
#define NCHANNELS (sizeof(brightness)/sizeof(brightness[0]))
void USART1_IRQHandler() {
static union packet rxbuf;
int isr = USART1->ISR;
USART1->RQR |= USART_RQR_RXFRQ;
/* Overrun detected? */
if (isr & USART_ISR_ORE) {
USART1->ICR = USART_ICR_ORECF; /* Acknowledge overrun */
//asm("bkpt"); /* uncomment for debug */
return;
}
if (!(isr & USART_ISR_RXNE)) {
//asm("bkpt"); /* uncomment for debug */
return;
}
/* Store received data */
uint8_t data = USART1->RDR;
rxbuf.data[rxpos] = data;
rxpos++;
/* If we finished receiving a packet, deal with it. */
if (rxpos == sizeof(union packet)) {
/* Check packet header */
if (rxbuf.set_step.cmd == 0x23 &&
/* bounds-check received channel number. This allows several driver boards to share one common serial bus */
rxbuf.set_step.step >= USART_CHANNEL_OFFX &&
rxbuf.set_step.step < USART_CHANNEL_OFFX+NCHANNELS) {
/* Calculate raw channel brightness value base address for logical channel */
uint32_t *out = &brightness[(rxbuf.set_step.step - USART_CHANNEL_OFFX)*4];
/* Correct RGBW raw channel ordering per logical channel according to SUB-D pinout used.
*
* (matti) (treppe)
* weiß blau
* rot weiß
* grün rot
* blau grün
*/
out[1] = rxbuf.set_step.rgbw[0];
out[2] = rxbuf.set_step.rgbw[1];
out[3] = rxbuf.set_step.rgbw[2];
out[0] = rxbuf.set_step.rgbw[3];
}
/* Reset receive data counter */
rxpos = 0;
}
/* Reset usart timeout handler */
TIM3->CNT = 0;
TIM3->CR1 |= TIM_CR1_CEN;
}
/* Misc IRQ handlers */
void NMI_Handler(void) {
}
void HardFault_Handler(void) {
for(;;);
}
void SVC_Handler(void) {
}
void PendSV_Handler(void) {
}
void SysTick_Handler(void) {
static int n = 0;
sys_time++;
if (n++ == 1000) {
n = 0;
sys_time_seconds++;
}
}
/* Misc stuff for nostdlib linking */
void _exit(int status) { while (23); }
void *__bss_start__;
void *__bss_end__;
int __errno;
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