diff --git a/tmcdriver/tmc/tmc_reg_cache.hpp b/tmcdriver/tmc/tmc_reg_cache.hpp
index 8517808..319a051 100644
--- a/tmcdriver/tmc/tmc_reg_cache.hpp
+++ b/tmcdriver/tmc/tmc_reg_cache.hpp
@@ -14,9 +14,9 @@ class TMCReg {
  private:
   /* data */
  public:
-  uint8_t flag = 0;
-  uint8_t reg  = 0;
-  uint8_t val  = 0;
+  uint8_t  flag = 0;
+  uint8_t  reg  = 0;
+  int32_t val  = 0;
 
   void setActiveFlag() { flag = flag | 0x01; }
   bool isActive() { return flag & 0x01; }
@@ -27,7 +27,7 @@ class TMCReg {
 
 class TMCRegCache {
  public:
-  TMCReg cache[50];
+  TMCReg cache[20];
 
  public:
   void foreach (function<void(TMCReg* item)> fn) {
@@ -52,7 +52,7 @@ class TMCRegCache {
     return false;
   }
 
-  void setReg(uint8_t reg, uint8_t val) {
+  void setReg(uint8_t reg, int32_t val) {
     TMCReg* item = findReg(reg);
     if (item) {
       item->val = val;