From f94aca6887ea4be605bc2c1c1069f8c5b1c0c66f Mon Sep 17 00:00:00 2001
From: Gregor Riepl <onitake@gmail.com>
Date: Sat, 6 Mar 2021 13:08:33 +0100
Subject: [PATCH] Document display interface commands

---
 README.md  | 20 +++++++++++++++++++-
 messages.h | 12 ++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 4a9be6e..5b23bd1 100644
--- a/README.md
+++ b/README.md
@@ -86,9 +86,25 @@ cd poweriface/firmware/
 make flash
 ```
 
+### display
+
+VFD (vaccum fluorescent display) interface.
+
+This module requires firmware. Connect an Atmel programmer to the ISP header
+of the poweriface board, make sure the programming jumper is shorted and run:
+
+```shell
+cd display
+make flash
+```
+
+This module provides a direct interface to the display controller's instruction
+and data registers. Refer to the 16T202DA1J data sheet, or any NEC dot matrix
+display controller data sheet for instruction codes and memory layout.
+
 ### sensor
 
-Environment sensor interface.
+Environment sensor interface. Unused at the moment.
 
 ### wiring
 
@@ -189,5 +205,7 @@ This is the list of supported message IDs:
 |------------|------------|------------|--------------|------------|-------------------------|-------------|
 | 0x10       | feedback   | any        | yes          | 2          | 0b00000KJI 0bHGFEDCBA   | Feedback module status report (A..E = end switch D..H, F..J = empty switch D..H, K = reset switch, 0 = off, 1 = on) |
 | 0x11       | poweriface | any        | yes          | 2          | 0bHHHHHHHH 0bLLLLLLLL   | Power module status report (0xHHLL are the contents of the 16-bit shift register) |
+| 0x12       | display    | any        | yes          | 1          | 0bHGFEDCBA              | Display module button status (A..H = button 0..7, 0 = off, 1 = on) |
 | 0x21       | controller | poweriface | no           | 1          | 0b00000MMM              | Start dispensing from slot M (1-5) or stop all dispensers (M = 0) |
+| 0x22       | controller | display    | no           | 1-8        | 0bAAAAAAAA 0bDDDDDDDD*  | Write address A into display instruction register and data bytes D (0-7 bytes) into data register |
 | 0x4f       | any        | any        | no           | 1          | 0b0000000E              | Enable (E = 1) or disable (E = 0) automatic status updates on all modules |
diff --git a/messages.h b/messages.h
index 737be34..e071116 100644
--- a/messages.h
+++ b/messages.h
@@ -5,6 +5,7 @@
 
 #define CAN_HOSTID_FEEDBACK 0x000
 #define CAN_HOSTID_POWER 0x001
+#define CAN_HOSTID_DISPLAY 0x002
 #define CAN_HOSTID_BROADCAST 0x00f
 #define CAN_HOSTID_MASK 0x00f
 
@@ -40,6 +41,11 @@ typedef struct {
 	uint8_t bits[2];
 } can_msg_power_status_t;
 
+#define CAN_MSG_DISPLAY_STATUS 0x012
+typedef struct {
+	uint8_t buttons;
+} can_msg_display_status_t;
+
 #define CAN_MSG_POWER_DISPENSE 0x021
 typedef uint8_t can_msg_power_dispense_t;
 #define CAN_MSG_POWER_DISPENSE_OFF 0x00
@@ -49,6 +55,12 @@ typedef uint8_t can_msg_power_dispense_t;
 #define CAN_MSG_POWER_DISPENSE_SLOT4 0x04
 #define CAN_MSG_POWER_DISPENSE_SLOT5 0x05
 
+#define CAN_MSG_DISPLAY_CMD 0x022
+typedef struct {
+	uint8_t address;
+	uint8_t data;
+} can_msg_display_cmd_t;
+
 #define CAN_MSG_AUTO_STATUS 0x04f
 typedef uint8_t can_msg_auto_status_t;
 #define CAN_MSG_AUTO_STATUS_DISABLE 0x00