diff --git a/.github/workflows/micropython.yml b/.github/workflows/micropython.yml
index 833f8f4..a367e10 100644
--- a/.github/workflows/micropython.yml
+++ b/.github/workflows/micropython.yml
@@ -62,7 +62,7 @@ jobs:
     - name: Install Arm GNU Toolchain (arm-none-eabi-gcc)
       uses: carlosperate/arm-none-eabi-gcc-action@v1
       with:
-        release: '9-2020-q2'
+        release: '13.3.Rel1'
 
     - name: "CCache: Install"
       run: |
diff --git a/drivers/dvhstx/dvhstx.cpp b/drivers/dvhstx/dvhstx.cpp
index 6121673..7b62a97 100644
--- a/drivers/dvhstx/dvhstx.cpp
+++ b/drivers/dvhstx/dvhstx.cpp
@@ -70,7 +70,7 @@ static inline __attribute__((always_inline)) uint32_t render_char_line(int c, in
 // Lists are padded with NOPs to be >= HSTX FIFO size, to avoid DMA rapidly
 // pingponging and tripping up the IRQs.
 
-static uint32_t vblank_line_vsync_off[] = {
+static const uint32_t vblank_line_vsync_off_src[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V1_H1,
     HSTX_CMD_RAW_REPEAT,
@@ -78,8 +78,9 @@ static uint32_t vblank_line_vsync_off[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V1_H1
 };
+static uint32_t vblank_line_vsync_off[count_of(vblank_line_vsync_off_src)];
 
-static uint32_t vblank_line_vsync_on[] = {
+static const uint32_t vblank_line_vsync_on_src[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V0_H1,
     HSTX_CMD_RAW_REPEAT,
@@ -87,8 +88,9 @@ static uint32_t vblank_line_vsync_on[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V0_H1
 };
+static uint32_t vblank_line_vsync_on[count_of(vblank_line_vsync_on_src)];
 
-static uint32_t vactive_line_header[] = {
+static const uint32_t vactive_line_header_src[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V1_H1,
     HSTX_CMD_RAW_REPEAT,
@@ -97,8 +99,9 @@ static uint32_t vactive_line_header[] = {
     SYNC_V1_H1,
     HSTX_CMD_TMDS      
 };
+static uint32_t vactive_line_header[count_of(vactive_line_header_src)];
 
-static uint32_t vactive_text_line_header[] = {
+static const uint32_t vactive_text_line_header_src[] = {
     HSTX_CMD_RAW_REPEAT,
     SYNC_V1_H1,
     HSTX_CMD_RAW_REPEAT,
@@ -114,6 +117,7 @@ static uint32_t vactive_text_line_header[] = {
     BLACK_PIXEL_B,
     HSTX_CMD_TMDS
 };
+static uint32_t vactive_text_line_header[count_of(vactive_text_line_header_src)];
 
 #define NUM_FRAME_LINES 2
 #define NUM_CHANS 3
@@ -572,8 +576,21 @@ void DVHSTX::clear()
     memset(frame_buffer_back, 0, frame_width * frame_height * frame_bytes_per_pixel);
 }
 
+DVHSTX::DVHSTX()
+{
+    // Always use the bottom channels
+    dma_claim_mask((1 << NUM_CHANS) - 1);
+}
+
 bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
 {
+    if (inited) reset();
+
+    ch_num = 0;
+    line_num = -1;
+    v_scanline = 2;
+    flip_next = false;
+
     display_width = width;
     display_height = height;
     frame_width = width;
@@ -646,7 +663,7 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
     }
 
     if (!timing_mode) {
-        printf("Unsupported resolution %dx%d", width, height);
+        dvhstx_debug("Unsupported resolution %dx%d", width, height);
         return false;
     }
 
@@ -666,19 +683,23 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
     v_repeat = 1 << v_repeat_shift;
     h_repeat = 1 << h_repeat_shift;
 
+    memcpy(vblank_line_vsync_off, vblank_line_vsync_off_src, sizeof(vblank_line_vsync_off_src));
     vblank_line_vsync_off[0] |= timing_mode->h_front_porch;
     vblank_line_vsync_off[2] |= timing_mode->h_sync_width;
     vblank_line_vsync_off[4] |= timing_mode->h_back_porch + timing_mode->h_active_pixels;
 
+    memcpy(vblank_line_vsync_on, vblank_line_vsync_on_src, sizeof(vblank_line_vsync_on_src));
     vblank_line_vsync_on[0] |= timing_mode->h_front_porch;
     vblank_line_vsync_on[2] |= timing_mode->h_sync_width;
     vblank_line_vsync_on[4] |= timing_mode->h_back_porch + timing_mode->h_active_pixels;
 
+    memcpy(vactive_line_header, vactive_line_header_src, sizeof(vactive_line_header_src));
     vactive_line_header[0] |= timing_mode->h_front_porch;
     vactive_line_header[2] |= timing_mode->h_sync_width;
     vactive_line_header[4] |= timing_mode->h_back_porch;
     vactive_line_header[6] |= timing_mode->h_active_pixels;
 
+    memcpy(vactive_text_line_header, vactive_text_line_header_src, sizeof(vactive_text_line_header_src));
     vactive_text_line_header[0] |= timing_mode->h_front_porch;
     vactive_text_line_header[2] |= timing_mode->h_sync_width;
     vactive_text_line_header[4] |= timing_mode->h_back_porch;
@@ -706,7 +727,7 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
         line_bytes_per_pixel = 14;
         break;
     default:
-        printf("Unsupported mode %d", (int)mode);
+        dvhstx_debug("Unsupported mode %d", (int)mode);
         return false;
     }
 
@@ -752,6 +773,12 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
         }
     }
 
+    // Ensure HSTX FIFO is clear
+    reset_block_num(RESET_HSTX);
+    sleep_us(10);
+    unreset_block_num_wait_blocking(RESET_HSTX);
+    sleep_us(10);
+
     switch (mode) {
     case MODE_RGB565:
         // Configure HSTX's TMDS encoder for RGB565
@@ -830,7 +857,7 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
         break;
 
     default:
-        printf("Unsupported mode %d", (int)mode);
+        dvhstx_debug("Unsupported mode %d", (int)mode);
         return false;
     }
 
@@ -871,9 +898,6 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
 
     dvhstx_debug("GPIO configured\n");
 
-    // Always use the bottom channels
-    dma_claim_mask((1 << NUM_CHANS) - 1);
-
     // The channels are set up identically, to transfer a whole scanline and
     // then chain to the next channel. Each time a channel finishes, we
     // reconfigure the one that just finished, meanwhile the other channel(s)
@@ -918,6 +942,7 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
 
     dvhstx_debug("DMA channels claimed\n");
 
+    dma_hw->intr = (1 << NUM_CHANS) - 1;
     dma_hw->ints2 = (1 << NUM_CHANS) - 1;
     dma_hw->inte2 = (1 << NUM_CHANS) - 1;
     if (is_text_mode) irq_set_exclusive_handler(DMA_IRQ_2, dma_irq_handler_text);
@@ -934,9 +959,34 @@ bool DVHSTX::init(uint16_t width, uint16_t height, Mode mode_)
 
     dvhstx_debug("Frame buffer filled\n");
 
+    inited = true;
     return true;
 }
 
+void DVHSTX::reset() {
+    if (!inited) return;
+    inited = false;
+
+    hstx_ctrl_hw->csr = 0;
+
+    irq_set_enabled(DMA_IRQ_2, false);
+    irq_remove_handler(DMA_IRQ_2, irq_get_exclusive_handler(DMA_IRQ_2));
+
+    for (int i = 0; i < NUM_CHANS; ++i)
+        dma_channel_abort(i);
+
+    if (font_cache) {
+        free(font_cache);
+        font_cache = nullptr;
+    }
+    free(line_buffers);
+
+#ifndef MICROPY_BUILD_TYPE
+    free(frame_buffer_display);
+    free(frame_buffer_back);
+#endif
+}
+
 void DVHSTX::flip_blocking() {
     wait_for_vsync();
     flip_now();
diff --git a/drivers/dvhstx/dvhstx.hpp b/drivers/dvhstx/dvhstx.hpp
index fcfbabd..4c75899 100644
--- a/drivers/dvhstx/dvhstx.hpp
+++ b/drivers/dvhstx/dvhstx.hpp
@@ -59,14 +59,12 @@ namespace pimoroni {
     uint16_t frame_width = 320;
     uint16_t frame_height = 180;
     uint8_t frame_bytes_per_pixel = 2;
-    uint8_t bank = 0;
     uint8_t h_repeat = 4;
     uint8_t v_repeat = 4;
     Mode mode = MODE_RGB565;
 
   public:
-    DVHSTX()
-    {}
+    DVHSTX();
 
     //--------------------------------------------------
     // Methods
@@ -95,6 +93,7 @@ namespace pimoroni {
       void clear();
 
       bool init(uint16_t width, uint16_t height, Mode mode = MODE_RGB565);
+      void reset();
 
       // Wait for vsync and then flip the buffers
       void flip_blocking();
@@ -118,7 +117,7 @@ namespace pimoroni {
 
       uint8_t* frame_buffer_display;
       uint8_t* frame_buffer_back;
-      uint32_t* font_cache;
+      uint32_t* font_cache = nullptr;
 
       uint16_t* point_to_ptr16(const Point &p) const {
         return ((uint16_t*)frame_buffer_back) + (p.y * (uint32_t)frame_width) + p.x;
@@ -143,6 +142,8 @@ namespace pimoroni {
       volatile int v_scanline = 2;
       volatile bool flip_next;
 
+      bool inited = false;
+
       uint32_t* line_buffers;
       const struct dvi_timing* timing_mode;
       int v_inactive_total;
diff --git a/modules/picographics/picographics.cpp b/modules/picographics/picographics.cpp
index 0bc9ece..7a1ba51 100644
--- a/modules/picographics/picographics.cpp
+++ b/modules/picographics/picographics.cpp
@@ -123,7 +123,13 @@ mp_obj_t ModPicoGraphics_make_new(const mp_obj_type_t *type, size_t n_args, size
 }
 
 mp_obj_t ModPicoGraphics__del__(mp_obj_t self_in) {
-    //dv_display.reset();
+    ModPicoGraphics_obj_t *self = MP_OBJ_TO_PTR2(self_in, ModPicoGraphics_obj_t);
+
+    dv_display.reset();
+    if (self->graphics) {
+        m_del_class(PicoGraphicsDVHSTX, self->graphics);
+        self->graphics = nullptr;
+    }
     return mp_const_none;
 }