diff --git a/main/u8g2_esp32_hal.c b/main/u8g2_esp32_hal.c
index 3147d05..a580dcd 100644
--- a/main/u8g2_esp32_hal.c
+++ b/main/u8g2_esp32_hal.c
@@ -110,14 +110,17 @@ uint8_t u8g2_esp32_spi_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void
     return 0;
 } // u8g2_esp32_spi_byte_cb
 
+
 /*
  * HAL callback function as prescribed by the U8G2 library.  This callback is invoked
  * to handle I2C communications.
  */
 uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void *arg_ptr)
 {
+    #define TXBUF_SIZE 32
+    static uint8_t txbuf[TXBUF_SIZE];
+    static uint8_t *txbuf_ptr;
     // ESP_LOGV(TAG, "i2c_cb: Received a msg: %d, arg_int: %d, arg_ptr: %p", msg, arg_int, arg_ptr);
-
     switch (msg)
     {
     case U8X8_MSG_BYTE_SET_DC:
@@ -157,14 +160,16 @@ uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void
     case U8X8_MSG_BYTE_SEND:
     {
         uint8_t *data_ptr = (uint8_t *)arg_ptr;
-        ESP_LOG_BUFFER_HEXDUMP(TAG, data_ptr, arg_int, ESP_LOG_VERBOSE);
+        size_t data_len = (size_t) arg_int;
+        // ESP_LOGV(TAG, "U8x8_MSG_BYTE_SEND. txbuf len: %d", txbuf_ptr - txbuf);
+        // ESP_LOG_BUFFER_HEXDUMP(TAG, data_ptr, data_len, ESP_LOG_VERBOSE);
 
-        while (arg_int > 0)
-        {
-            ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, *data_ptr, ACK_CHECK_EN));
-            data_ptr++;
-            arg_int--;
+        if (txbuf_ptr + data_len >= txbuf_ptr + TXBUF_SIZE) {
+            ESP_LOGE(TAG, "txbuf overflow");
+            return 0;
         }
+        memcpy(txbuf_ptr, data_ptr, data_len);
+        txbuf_ptr += data_len;
         break;
     }
 
@@ -175,12 +180,15 @@ uint8_t u8g2_esp32_i2c_byte_cb(u8x8_t *u8x8, uint8_t msg, uint8_t arg_int, void
         // ESP_LOGV(TAG, "Start I2C transfer to %02X.", i2c_address >> 1);
         ESP_ERROR_CHECK(i2c_master_start(handle_i2c));
         ESP_ERROR_CHECK(i2c_master_write_byte(handle_i2c, i2c_address | I2C_MASTER_WRITE, ACK_CHECK_EN));
+        txbuf_ptr = txbuf;
         break;
     }
 
     case U8X8_MSG_BYTE_END_TRANSFER:
     {
-        // ESP_LOGV(TAG, "End I2C transfer.");
+        // ESP_LOGV(TAG, "End I2C transfer. txbuf len: %d", txbuf_ptr - txbuf);
+        // ESP_LOG_BUFFER_HEXDUMP(TAG, txbuf, txbuf_ptr - txbuf, ESP_LOG_VERBOSE);
+        ESP_ERROR_CHECK(i2c_master_write(handle_i2c, txbuf, txbuf_ptr - txbuf, ACK_CHECK_EN));
         ESP_ERROR_CHECK(i2c_master_stop(handle_i2c));
         ESP_ERROR_CHECK(i2c_master_cmd_begin(I2C_MASTER_NUM, handle_i2c, I2C_TIMEOUT_MS / portTICK_RATE_MS));
         i2c_cmd_link_delete(handle_i2c);
diff --git a/main/u8g2_esp32_hal.h b/main/u8g2_esp32_hal.h
index 3763f20..e22a06d 100644
--- a/main/u8g2_esp32_hal.h
+++ b/main/u8g2_esp32_hal.h
@@ -18,7 +18,7 @@
 #define I2C_MASTER_NUM I2C_NUM_1    //  I2C port number for master dev
 #define I2C_MASTER_TX_BUF_DISABLE 0 //  I2C master do not need buffer
 #define I2C_MASTER_RX_BUF_DISABLE 0 //  I2C master do not need buffer
-#define I2C_MASTER_FREQ_HZ 50000    //  I2C master clock frequency
+#define I2C_MASTER_FREQ_HZ 400000    //  I2C master clock frequency
 #define ACK_CHECK_EN 0x1            //  I2C master will check ack from slave
 #define ACK_CHECK_DIS 0x0           //  I2C master will not check ack from slave