[EV3] Implement LED brightness control via software PWM on PRU1

bricks/_common/arm_none_eabi.mk

@@ -564,6 +564,7 @@ OBJ += $(addprefix $(BUILD)/, $(TI_AM1808_USB_SRC_C:.c=.o))
 OBJ += $(addprefix $(BUILD)/, $(EV3_SRC_S:.S=.o))
 $(addprefix $(BUILD)/, $(EV3_SRC_S:.S=.o)): CFLAGS += -D__ASSEMBLY__
 OBJ += $(BUILD)/pru_suart.bin.o
+OBJ += $(BUILD)/pru_ledpwm.bin.o
 endif
 
 # List of sources for qstr extraction
@@ -637,6 +638,11 @@ $(BUILD)/u-boot.bin:
 	$(Q)mkdir -p $(dir $@)
 	$(Q)curl -sL -o $@ https://github.com/pybricks/u-boot/releases/download/pybricks/v2.0.1/u-boot.bin
 	$(Q)echo "86ddad84f64d8aea85b4315fc1414bdec0bb0d46c92dbd3db45ed599e3a994cb  $@" | sha256sum -c --strict
+$(BUILD)/pru_ledpwm.bin:
+	$(ECHO) "Downloading pru_ledpwm.bin"
+	$(Q)mkdir -p $(dir $@)
+	$(Q)curl -sL -o $@ https://github.com/pybricks/pybricks-pru/releases/download/v0.0.1/pru_ledpwm.bin
+	$(Q)echo "c0138addb8ebb3d0f531499b6f45ccc71f524afbb6ce55ca3ab462a001ec28d2  $@" | sha256sum -c --strict
 
 MAKE_BOOTABLE_IMAGE = $(PBTOP)/bricks/ev3/make_bootable_image.py
 
@@ -668,6 +674,9 @@ $(BUILD)/firmware.zip: $(ZIP_FILES)
 $(BUILD)/pru_suart.bin.o: $(PBTOP)/lib/pbio/drv/uart/uart_ev3_pru_lib/pru_suart.bin
 	$(Q)$(OBJCOPY) -I binary -O elf32-littlearm -B arm \
 		--rename-section .data=.pru0,alloc,load,readonly,data,contents $^ $@
+$(BUILD)/pru_ledpwm.bin.o: $(BUILD)/pru_ledpwm.bin
+	$(Q)$(OBJCOPY) -I binary -O elf32-littlearm -B arm \
+		--rename-section .data=.pru1,alloc,load,readonly,data,contents $^ $@
 
 # firmware in DFU format
 $(BUILD)/%.dfu: $(BUILD)/%-base.bin

lib/pbio/drv/led/led_pwm.h

@@ -52,6 +52,8 @@ typedef struct {
     uint8_t scale_factor;
 } pbdrv_led_pwm_platform_data_t;
 
+#define PBDRV_LED_PWM_CHANNEL_INVALID   0xff
+
 // defined in platform/*/platform.c
 extern const pbdrv_led_pwm_platform_data_t pbdrv_led_pwm_platform_data[PBDRV_CONFIG_LED_PWM_NUM_DEV];
 

lib/pbio/drv/pwm/pwm_ev3.c

@@ -6,43 +6,75 @@
 #if PBDRV_CONFIG_PWM_TIAM1808
 
 #include <stdio.h>
+#include <string.h>
 
 #include <pbdrv/pwm.h>
 #include <pbdrv/gpio.h>
 #include <pbio/error.h>
 
+#include <tiam1808/hw/hw_syscfg0_AM1808.h>
+#include <tiam1808/hw/hw_types.h>
+#include <tiam1808/hw/soc_AM1808.h>
+#include <tiam1808/pruss.h>
+#include <tiam1808/psc.h>
+#include <tiam1808/timer.h>
+
 #include "../drv/pwm/pwm.h"
+#include "../../drv/led/led_pwm.h"
 #include "../../drv/pwm/pwm_ev3.h"
 #include "../../drv/gpio/gpio_ev3.h"
 
+// This needs to match the interface expected by the PRU firmware
+typedef struct shared_ram {
+    uint8_t pwms[PBDRV_PWM_EV3_NUM_CHANNELS];
+} shared_ram;
+static volatile shared_ram pru1_shared_ram __attribute__((section(".shared1")));
+
 static pbio_error_t pbdrv_pwm_tiam1808_set_duty(pbdrv_pwm_dev_t *dev, uint32_t ch, uint32_t value) {
     // Blue not available.
-    if (ch == 2) {
+    if (ch == PBDRV_LED_PWM_CHANNEL_INVALID) {
         return PBIO_SUCCESS;
     }
-    pbdrv_pwm_tiam1808_platform_data_t *priv = dev->priv;
-
-    // TODO: implement PWM. Just use GPIO for now.
-    pbdrv_gpio_t *gpio = (ch == 0) ? &priv->gpio_red : &priv->gpio_green;
-    if (value) {
-        pbdrv_gpio_out_high(gpio);
-    } else {
-        pbdrv_gpio_out_low(gpio);
-    }
+
+    pru1_shared_ram.pwms[ch] = value;
     return PBIO_SUCCESS;
 }
 
 static const pbdrv_pwm_driver_funcs_t pbdrv_pwm_tiam1808_funcs = {
     .set_duty = pbdrv_pwm_tiam1808_set_duty,
 };
 
+extern char _pru1_start;
+extern char _pru1_end;
+
+#define PINMUX_ALT_PRU1     4
+
 void pbdrv_pwm_tiam1808_init(pbdrv_pwm_dev_t *devs) {
-    for (int i = 0; i < PBDRV_CONFIG_PWM_TIAM1808_NUM_DEV; i++) {
-        devs[i].funcs = &pbdrv_pwm_tiam1808_funcs;
-        devs[i].priv = (pbdrv_pwm_tiam1808_platform_data_t *)&pbdrv_pwm_tiam1808_platform_data[i];
+    // Enable Timer0 "34" half to count up to 256 * 256
+    // This is used by the PRU to time the PWM
+    TimerPreScalarCount34Set(SOC_TMR_0_REGS, 0);
+    TimerPeriodSet(SOC_TMR_0_REGS, TMR_TIMER34, 256 * 256 - 1);
+    TimerEnable(SOC_TMR_0_REGS, TMR_TIMER34, TMR_ENABLE_CONT);
+
+    // Clear shared command memory
+    memset((void *)&pru1_shared_ram, 0, sizeof(shared_ram));
+
+    // Enable PRU1 and load its firmware
+    PSCModuleControl(SOC_PSC_0_REGS, HW_PSC_PRU, PSC_POWERDOMAIN_ALWAYS_ON, PSC_MDCTL_NEXT_ENABLE);
+    PRUSSDRVPruDisable(1);
+    PRUSSDRVPruReset(1);
+    unsigned int *fw_start = (unsigned int *)&_pru1_start;
+    uint32_t fw_sz = &_pru1_end - &_pru1_start;
+    PRUSSDRVPruWriteMemory(PRUSS0_PRU1_IRAM, 0, fw_start, fw_sz);
+    // Set constant table C30 to point to shared memory
+    PRUSSDRVPruSetCTable(1, 30, (((uint32_t)&pru1_shared_ram) >> 8) & 0xffff);
+    PRUSSDRVPruEnable(1);
+
+    devs[0].funcs = &pbdrv_pwm_tiam1808_funcs;
 
-        pbdrv_gpio_out_low(&pbdrv_pwm_tiam1808_platform_data[i].gpio_red);
-        pbdrv_gpio_out_low(&pbdrv_pwm_tiam1808_platform_data[i].gpio_green);
+    // Set GPIO alt modes for the PRU
+    for (int j = 0; j < PBDRV_PWM_EV3_NUM_CHANNELS; j++) {
+        pbdrv_gpio_alt(&pbdrv_pwm_tiam1808_platform_data.gpios[j], PINMUX_ALT_PRU1);
     }
 }
 

lib/pbio/drv/pwm/pwm_ev3.h

@@ -13,16 +13,16 @@
 #include <pbdrv/pwm.h>
 #include <pbdrv/gpio.h>
 
+#define PBDRV_PWM_EV3_NUM_CHANNELS  4
+
 /** Platform-specific device information. */
 typedef struct {
     uint8_t id;
-    pbdrv_gpio_t gpio_red;
-    pbdrv_gpio_t gpio_green;
+    pbdrv_gpio_t gpios[PBDRV_PWM_EV3_NUM_CHANNELS];
 } pbdrv_pwm_tiam1808_platform_data_t;
 
 // Defined in platform.c
-extern const pbdrv_pwm_tiam1808_platform_data_t
-    pbdrv_pwm_tiam1808_platform_data[PBDRV_CONFIG_PWM_TIAM1808_NUM_DEV];
+extern const pbdrv_pwm_tiam1808_platform_data_t pbdrv_pwm_tiam1808_platform_data;
 
 void pbdrv_pwm_tiam1808_init(pbdrv_pwm_dev_t *devs);
 

lib/pbio/platform/ev3/pbdrvconfig.h

@@ -66,7 +66,6 @@
 #define PBDRV_CONFIG_PWM                            (1)
 #define PBDRV_CONFIG_PWM_NUM_DEV                    (2)
 #define PBDRV_CONFIG_PWM_TIAM1808                   (1)
-#define PBDRV_CONFIG_PWM_TIAM1808_NUM_DEV           (2)
 
 #define PBDRV_CONFIG_RESET                          (1)
 #define PBDRV_CONFIG_RESET_EV3                      (1)

lib/pbio/platform/ev3/platform.c

@@ -72,8 +72,7 @@ enum {
 };
 
 enum {
-    PWM_DEV_0_TODO,
-    PWM_DEV_1_TODO,
+    PWM_DEV_0,
 };
 
 // LED
@@ -87,55 +86,53 @@ const pbdrv_led_dual_platform_data_t pbdrv_led_dual_platform_data[PBDRV_CONFIG_L
 };
 
 static const pbdrv_led_pwm_platform_color_t pbdrv_led_pwm_color = {
-    // TODO: PWM not yet implemented, so these values not used.
-    .r_factor = 1000,
-    .g_factor = 170,
-    .b_factor = 200,
-    .r_brightness = 174,
-    .g_brightness = 1590,
-    .b_brightness = 327,
+    // The red LED is much stronger than the green one, so leave green at 1000
+    // and adjust red until yellow looks good.
+    .r_factor = 150,
+    .g_factor = 1000,
+    .b_factor = 0,
+    // 1250 allows max brightness for an 8-bit PWM size (with scale_factor = 1).
+    // Increase to limit max brightness. Going lower will cause overflow.
+    .r_brightness = 1250,
+    .g_brightness = 1250,
+    .b_brightness = 0,
 };
 
 const pbdrv_led_pwm_platform_data_t pbdrv_led_pwm_platform_data[PBDRV_CONFIG_LED_PWM_NUM_DEV] = {
     {
         .color = &pbdrv_led_pwm_color,
         .id = LED_DEV_1_STATUS_LEFT,
-        .r_id = PWM_DEV_0_TODO,
+        .r_id = PWM_DEV_0,
         .r_ch = 0,
-        .g_id = PWM_DEV_0_TODO,
+        .g_id = PWM_DEV_0,
         .g_ch = 1,
         // Blue not available.
-        .b_id = PWM_DEV_0_TODO,
-        .b_ch = 2,
-        // TODO: PWM not yet implemented, so these values not used.
-        .scale_factor = 35,
+        .b_id = PWM_DEV_0,
+        .b_ch = PBDRV_LED_PWM_CHANNEL_INVALID,
+        .scale_factor = 1,
     },
     {
         .color = &pbdrv_led_pwm_color,
         .id = LED_DEV_2_STATUS_RIGHT,
-        .r_id = PWM_DEV_1_TODO,
-        .r_ch = 0,
-        .g_id = PWM_DEV_1_TODO,
-        .g_ch = 1,
+        .r_id = PWM_DEV_0,
+        .r_ch = 2,
+        .g_id = PWM_DEV_0,
+        .g_ch = 3,
         // Blue not available.
-        .b_id = PWM_DEV_1_TODO,
-        .b_ch = 2,
-        // TODO: PWM not yet implemented, so these values not used.
-        .scale_factor = 35,
+        .b_id = PWM_DEV_0,
+        .b_ch = PBDRV_LED_PWM_CHANNEL_INVALID,
+        .scale_factor = 1,
     },
 };
 
-const pbdrv_pwm_tiam1808_platform_data_t
-    pbdrv_pwm_tiam1808_platform_data[PBDRV_CONFIG_PWM_TIAM1808_NUM_DEV] = {
-    {
-        .id = PWM_DEV_0_TODO,
-        .gpio_red = PBDRV_GPIO_EV3_PIN(13, 11, 8, 6, 13),
-        .gpio_green = PBDRV_GPIO_EV3_PIN(14, 3, 0, 6, 7),
-    },
-    {
-        .id = PWM_DEV_1_TODO,
-        .gpio_red = PBDRV_GPIO_EV3_PIN(13, 15, 12, 6, 12),
-        .gpio_green = PBDRV_GPIO_EV3_PIN(13, 7, 4, 6, 14),
+const pbdrv_pwm_tiam1808_platform_data_t pbdrv_pwm_tiam1808_platform_data =
+{
+    .id = PWM_DEV_0,
+    .gpios = {
+        PBDRV_GPIO_EV3_PIN(13, 11, 8, 6, 13),
+        PBDRV_GPIO_EV3_PIN(14, 3, 0, 6, 7),
+        PBDRV_GPIO_EV3_PIN(13, 15, 12, 6, 12),
+        PBDRV_GPIO_EV3_PIN(13, 7, 4, 6, 14),
     },
 };
 

lib/pbio/platform/ev3/platform.ld

@@ -5,7 +5,8 @@ ENTRY(Entry)
 
 MEMORY
 {
-    SRAM       (rwx) : ORIGIN = 0x80000000, LENGTH = 128K
+    SRAM_PRU0  (rw)  : ORIGIN = 0x80000000, LENGTH = 64K
+    SRAM_PRU1  (rw)  : ORIGIN = 0x80010000, LENGTH = 64K
     DDR_unused (rwx) : ORIGIN = 0xC0000000, LENGTH = 0x8000
     DDR        (rwx) : ORIGIN = 0xC0008000, LENGTH = (64M - 0x8000)
     ARM_LRAM   (rwx) : ORIGIN = 0xFFFF0000, LENGTH = 8K
@@ -38,6 +39,10 @@ SECTIONS
         KEEP(*(.pru0));
         . = ALIGN(4);
         _pru0_end = .;
+        _pru1_start = .;
+        KEEP(*(.pru1));
+        . = ALIGN(4);
+        _pru1_end = .;
     } >DDR
 
     .data :
@@ -79,4 +84,14 @@ SECTIONS
         . = . + _minimal_stack_size; /* will cause linker error if there is not enough space for stack. */
         . = ALIGN(4);
     } > DDR
+
+    /* Shared on-chip SRAM */
+    .shared0 (NOLOAD) :
+    {
+        *(.shared0)
+    } > SRAM_PRU0
+    .shared1 (NOLOAD) :
+    {
+        *(.shared1)
+    } > SRAM_PRU1
 }

lib/tiam1808/drivers/pruss.c

@@ -332,6 +332,53 @@ void PRUSSDRVIntcSetHmr(unsigned short channel,
             | (((host) & 0xF) << (((channel) & 0x3) << 3));
 }
 
+/**
+ * \brief   Set PRU constant table entries
+ *
+ * \param   pruNum          PRU instance number[0 or 1].
+ * \param   ctable_idx      Index into constants table
+ * \param   value           Value to set
+ *
+ * \return   0 in case of success, -1 otherwise.
+ */
+int PRUSSDRVPruSetCTable(unsigned int pruNum,
+                         unsigned int ctable_idx,
+                         unsigned int value)
+{
+    unsigned int regAddr;
+
+    if(pruNum == 0)
+        regAddr = PRU0CONTROL_PHYS_BASE;
+    else if(pruNum == 1)
+        regAddr = PRU1CONTROL_PHYS_BASE;
+    else
+        return -1;
+
+    switch (ctable_idx) {
+    case 24:
+        HWREG(regAddr + PRU_CONTABBLKIDX0) = (HWREG(regAddr + PRU_CONTABBLKIDX0) & ~0xf) | (value & 0xf);
+        break;
+    case 25:
+        HWREG(regAddr + PRU_CONTABBLKIDX0) = (HWREG(regAddr + PRU_CONTABBLKIDX0) & ~0xf0000) | ((value & 0xf) << 16);
+        break;
+    case 28:
+        HWREG(regAddr + PRU_CONTABPROPTR0) = (HWREG(regAddr + PRU_CONTABPROPTR0) & ~0xffff) | (value & 0xffff);
+        break;
+    case 29:
+        HWREG(regAddr + PRU_CONTABPROPTR0) = (HWREG(regAddr + PRU_CONTABPROPTR0) & ~0xffff0000) | ((value & 0xffff) << 16);
+        break;
+    case 30:
+        HWREG(regAddr + PRU_CONTABPROPTR1) = (HWREG(regAddr + PRU_CONTABPROPTR1) & ~0xffff) | (value & 0xffff);
+        break;
+    case 31:
+        HWREG(regAddr + PRU_CONTABPROPTR1) = (HWREG(regAddr + PRU_CONTABPROPTR1) & ~0xffff0000) | ((value & 0xffff) << 16);
+        break;
+    default:
+        return -1;
+    }
+    return 0;
+}
+
 void ICSS_Init(void)
 {
 	/*	ICSS PRCM Enable	*/

lib/tiam1808/tiam1808/pruss.h

@@ -91,6 +91,13 @@ extern "C" {
 #define PRU1IRAM_PHYS_BASE            0x01C3C000
 #endif
 
+/*
+ * PRUSS control and status registers offsets
+ */
+#define PRU_CONTABBLKIDX0       0x20
+#define PRU_CONTABPROPTR0       0x28
+#define PRU_CONTABPROPTR1       0x2C
+
 #define PRU_EVTOUT_0            0
 #define PRU_EVTOUT_1            1
 #define PRU_EVTOUT_2            2
@@ -258,6 +265,10 @@ void PRUSSDRVIntcSetCmr(unsigned short sysevt,
 void PRUSSDRVIntcSetHmr(unsigned short channel,
                         unsigned short host);
 
+int PRUSSDRVPruSetCTable(unsigned int pruNum,
+                         unsigned int ctable_idx,
+                         unsigned int value);
+
 void ICSS_Init(void);
 
 // #ifdef  AM33XX