diff --git a/src/dmesg.c b/src/dmesg.c
index f1a205b..22b9613 100644
--- a/src/dmesg.c
+++ b/src/dmesg.c
@@ -46,6 +46,8 @@ void codal_dmesgf(const char *format, ...) {
 }
 
 void codal_vdmesg(const char *format, va_list ap) {
+    // if (format[0] == '!')
+    //    pin_pulse(PIN_X0, 1);
     char tmp[80];
     codal_vsprintf(tmp, sizeof(tmp) - 1, format, ap);
     int len = strlen(tmp);
@@ -135,4 +137,3 @@ int codal_sprintf(char *dst, unsigned dstsize, const char *format, ...) {
     va_end(arg);
     return r;
 }
-
diff --git a/stm32/rtc.c b/stm32/rtc.c
index ef709cf..7aea719 100644
--- a/stm32/rtc.c
+++ b/stm32/rtc.c
@@ -51,7 +51,7 @@ void rtc_sync_time() {
 
     if (!ctx->needsSync)
         return;
-    pin_set(PIN_PWR_STATE, 1);
+
     target_disable_irq();
     uint16_t subsecond;
     uint8_t newSecond;
@@ -65,6 +65,7 @@ void rtc_sync_time() {
     }
     subsecond = ctx->presc - subsecond;
     if (newSecond != ctx->lastSecond) {
+        // this branch adds ~4us
         int diff = 60 + BCD(newSecond, 3) - BCD(ctx->lastSecond, 3);
         if (diff >= 60)
             diff -= 60;
diff --git a/stm32/uart.c b/stm32/uart.c
index a2b4231..01c57b1 100644
--- a/stm32/uart.c
+++ b/stm32/uart.c
@@ -211,10 +211,10 @@ void uart_init() {
     USART_UART_Init();
 }
 
-static void check_idle(void) {
-    if (LL_USART_IsEnabled(USARTx))
-        jd_panic();
-}
+// static void check_idle(void) {
+//    if (LL_USART_IsEnabled(USARTx))
+//        jd_panic();
+//}
 
 int uart_wait_high() {
     int timeout = 5000;
@@ -282,10 +282,7 @@ int uart_start_tx(const void *data, uint32_t numbytes) {
 
 void uart_start_rx(void *data, uint32_t maxbytes) {
     // DMESG("start rx");
-    check_idle();
-
-    exti_disable(PIN_MASK(UART_PIN));
-    exti_clear(PIN_MASK(UART_PIN));
+    // check_idle();
 
     uartOwnsPin(1);
     LL_USART_DisableDirectionTx(USARTx);
@@ -300,6 +297,9 @@ void uart_start_rx(void *data, uint32_t maxbytes) {
     LL_DMA_SetDataLength(DMA1, LL_DMA_CHANNEL_5, maxbytes);
     LL_USART_EnableDMAReq_RX(USARTx);
     LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_5);
+
+    exti_disable(PIN_MASK(UART_PIN));
+    exti_clear(PIN_MASK(UART_PIN));
 }
 
 // this is only enabled for error events